text:
Talk:MMIX

"an MMIX chip"
Quote: There are 256 general purpose architectural registers in an MMIX chip

What "chip" is this? I am aware of no hardware implementation. Liam Proven (talk) 13:45, 31 December 2009 (UTC)

Name fix, feature request
Should MIXX be changed to MMIX? --Hirzel

Quickly noticed, Hirzel! Have fixed it. Also, I have foolishly re-ambiguated MIX by creating a "MIX" node, instead of the intended "MIX architecture" node. There is also a "Mix" node in the music category. I am not sure what the policy on case-sensitivity is... --Ejrh

 * Thank you for clarifying. A wish - It would be nice to have a graphical representation of the MMIX architecture and perhaps some code examples. --Hirzel

Article format (factoring)
I noticed there seems to be a disagreement on the preferred format of the article as regards textual factoring, i.e. what part of the text fits naturally in the intro blurb vs in the article's body (see history). Naturally, since I made the refactoring which has now been reverted, I would like to get some comments on that. My reason to refactor was that I thought a short background (i.e. mention of original MIX) was better placed in the intro paragraph, and that elaboration of MMIX should be placed in the body, where one could also put even more info if wanted. The wording as such was fine. --Wernher 19:16, 24 Mar 2004 (UTC)

 * (Woops, sorry for not getting back on this sooner.) Looking back at your changes, there was an issue with the wording.
 * First sentence: I removed the word "fictional", as MMIX is real.
 * Second sentence: Since MMIX is the topic, we should first talk about MMIX, rather than MIX. What is it? What is it used for? Those are the questions that should be answered in the first paragraph.
 * (Then, in the second paragraph, we can talk about MIX.)

 * I guess I see your point. More people will have heard of MIX than MMIX, so you could start off talking about MIX. But it could be confusing to people who have not come across either of them. Also, you called Knuth's books "textbooks". :) I couldn't let you get away with that. Hehe. (See ) -- Dan Matic 00:24, 30 Apr 2004 (UTC)

 * Hello, thanks for replying. I now see you point about the intro paragraph, so no problems with that wrt contents. As pertains MMIX being a fictional computer or not, however, I put in that word to distinguish MMIX from 'real/commercial' virtual computers, i.e. actual software products emulating real-life computers, so that people can use them to run 'real' software. An example is IBM's VM/CMS stuff on the S/360/370 range. Assuming I haven't misunderstood things, MMIX is (like MIX) an educational/experimental machine architecture never meant to be realized and used for running production software. Hence my use of 'fictional' as a distinguishing adjective. --Wernher 22:55, 30 Apr 2004 (UTC)

 * I guess you're right, but I still don't think the word 'fictional' fits. :) I suppose I should add more content and explain that MMIX is primarily intended to be an educational tool. (It's being used in various university courses to teach programming and compiler design.) Then again, I doubt many people would be reading this page. I'm fascinated that you've even stumbled upon it! -- Dan Matic 16:20, 1 May 2004 (UTC)

Hello, world
Has anyone else noticed that, contrary to the article, there is not an example on Hello_world_program as of 14:43, 5 Feb 2005 (UTC)?

Yes, this was my fault, but I've added it now :) 145.97.223.187 15:28, 6 Mar 2005 (UTC)

MMIX and self-modifying instructions
At http://en.wikipedia.org/wiki/Self-modifying_code we read:

Donald Knuth's original MIX architecture also used self-modifying code to implement subroutine calls.

Am I to infer that the same is not true of MMIX? If so, some elaboration/explanation here and/or there might be helpful.

But actually, now that I read it more closely, it sounds like it was not true even in MIX, except in the original conception.

Toddcs (talk) 13:24, 3 March 2008 (UTC)

 * MIX uses self-modifying code for subroutine calls. MMIX does not. I removed the original qualification from the sentence you point out to clarify that this is true for the final version of MIX. -- Schapel (talk) 13:45, 3 March 2008 (UTC)

Please define "tripping" and "trapping"
I suspect that the article doesn't mean "tripping" in the psychedelic experience sense, so it would be nice if the trip (and trap) terms was defined in the article. 188.60.234.146 (talk) 21:31, 21 March 2010 (UTC)

 * I agree that "trapping" and "tripping" terms should be defined in this article, so I added a paragraph describing them (with a reference). Feel free to continue to make improvements to this article. --DavidCary (talk) 04:30, 19 April 2017 (UTC)

Hardware implementation
The article states briefly that there is no hardware implementation, but why isn't there? Wouldn't it be a great teaching tool? It wouldn't have to be anything special in terms of speed or complexity or physical compactness - the point after all would be to illustrate very close-to-the-metal concepts to people wishing to understand them, rather than create a commercially viable new computing architecture. Second question: when Knuth says "I was careful to include all of the complexities needed to achieve high performance in practice, so that MMIX could in principle be built and even perhaps be competitive with some of the fastest general-purpose computers in the marketplace" did he really think it could become a popular new architecture? If so, and given that Knuth is a pretty intelligent guy, why did it not come to be regarded as a viable option for widespread use? Beorhtwulf (talk) 22:32, 28 February 2011 (UTC)

 * Dear Beorhtwulf,

 * We all expect to see the MMIX description published in the 4th edition of The Art of Computer Programming, Volume 1.

 * But since that hasn't been published yet, don't you think it's a little premature to be asking why it failed?

 * There is a popular misconception that "competitive with some of the fastest general-purpose computers in the marketplace" has something to do with "widespread use".

 * It doesn't.

 * AMD and Intel make some of the fastest CPUs available in the marketplace -- "competitive with some of the fastest general-purpose computers in the marketplace".
 * You might think that would lead to them being the most widely used CPUs -- "widespread use".

 * But they aren't.
 * A certain alternative 32-bit architecture sells more chips per year than the per-year sales of all of AMD's and Intel's 32-bit (x86 architecture) and 64-bit (x86-64 architecture) CPUs combined.

 * Pretty much all of those 32-bit and 64-bit CPUs are faster than any 8-bit CPU, and yet the last time I checked, 8-bit CPUs sold per year still far outnumbered all 32-bit and 64-bit processors sold per year combined (microprocessor).

 * Therefore, just because something is "competitive with some of the fastest general-purpose computers in the marketplace" has little to do with "widespread use".

 * --DavidCary (talk) 01:41, 7 December 2013 (UTC)

 * Thank you DavidCary for your reply. I hadn't appreciated that a description hadn't yet been published. The article reads as if MMIX has been set out in some detail by Knuth, such that (for all this general reader knows) it would be theoretically possible for someone to go and implement it. Perhaps the article could be updated to reflect what you say about the architecture not being fully documented.
 * I accept what you say about technical superiority not translating into commercial adoption. I suppose I had thought MMIX, if well conceived, might have at least found use in some specialist branch of applied computing in which its performance merits would outweigh any need to run the vast back catalogue of software written with other architectures in mind. Beorhtwulf (talk) 21:45, 8 March 2017 (UTC)

What about the instruction pointer register aka program counter register?
Surely there must be an instruction pointer in the guise of a 33rd hidden, special register. Don Knuth's original documentation doesn't mention this register, but his software makes use of the at-sign (@). Maybe it's unnecessary to mention the @-register. Any opinions? -- Ximalas (talk) 16:09, 17 October 2010 (UTC)

 * I agree that this article should a few words about the program counter (instruction pointer) of the MMIX.
 * There is also surely an instruction register and likely several other internal microarchitectural registers.
 * Some style guides seem to recommend discussing only the instruction set and programmer-visible registers when describing a CPU to programmers, leaving out implementation details such as microarchitectural registers.
 * Apparently someone feels that the instruction pointer is not one of the "programmer-visible" registers in the MMIX.
 * Is there some reason Ximalas suspects the PC is a 33rd special register, rather than a 37th special register, or some other category of register entirely?
 * --DavidCary (talk) 06:40, 30 November 2013 (UTC)
 * I originally thought it would be appropriate to mention such a register. In hindsight, after reading the remarks on this page and knowing that every MMIX program operates on virtual addresses, that's your address, be it your code or your data. Apparently there is no way of determining the physical addresses for each invocation other than through the services of the hypothetical operating system NNIX. Ximalas (talk) 19:35, 3 January 2014 (UTC)

title: Talk:MMIX


text:
Piaggio

Piaggio Group (Piaggio Group ) is an Italian motor vehicle manufacturer, which produces a range of two-wheeled motor vehicles and compact commercial vehicles under four brands: Piaggio, Vespa, Aprilia, Moto Guzzi and Derbi. Its corporate headquarters are located in Pontedera, Italy. The company was founded by Rinaldo Piaggio in 1884, initially producing locomotives and railway carriages.

Piaggio Group's subsidiaries employ a total of 7,053 employees and produced a total of 519,700 vehicles in 2014. The manufacturer has six research-and-development centres and operates in over 50 countries.

History
In 1882, Enrico Piaggio purchased land in Sestri Ponente (Genoa) to set up a timber yard. Two years later, in 1884, his 20-year-old son, Rinaldo Piaggio (1864–1938), founded Piaggio & C. The company initially built locomotives and railway carriages. In 1917, towards the end of World War I, Rinaldo Piaggio turned to the military sector: The company started to produce MAS anti-submarine motorboats, aeroplanes and seaplanes under Ansaldo, Macchi, Caproni, and Dornier licenses. Later the company progressed to vehicles constructed according to Piaggio's own drawings.

Between 1937 and 1939 Piaggio achieved 21 world records with its aircraft and engines built at the company's new factory in Pontedera, culminating in the four-engine Piaggio P.108 bomber.

Rinaldo died in 1938, by which time Piaggio was owned by multiple shareholders within the family, along with the entrepreneur Attilio Odero. Management of the company passed to his sons Enrico and Armando.

By 1940 Piaggio was manufacturing trains, nautical fittings, aircraft engines, aeroplanes, trucks, trams, buses, funiculars and aluminium windows and doors. The Pontedera plant was destroyed by Allied bombing and production activities were relocated to the Biella area.

After the war, Enrico Piaggio decided to diversify the company's activities outside the aeronautical industry to address a perceived need for a modern, affordable mode of transport for the Italian mass market. The first attempt, based on a small motorcycle made for parachutists, was known as the MP5 and nicknamed the "Paperino" (the Italian name for Donald Duck) because of its strange shape. Ultimately Enrico Piaggio did not like it and asked Corradino D'Ascanio to redesign it.

D'Ascanio, an aeronautical engineer responsible for the design and construction of the first modern helicopter by Agusta, was not naturally enthusiastic about motorcycles, judging them to be uncomfortable and bulky, with wheels that were difficult to change after a puncture. When asked to design a motorcycle for Ferdinando Innocenti, D'Ascanio had come up with a step through scooter design but D'Ascanio and Innocenti disagreed over use of a pressed steel frame rather than tubular, so D'Ascanio took his design to Piaggio. Innocenti would ultimately use D'Ascanio's original design for their Lambretta scooter.

Piaggio asked D'Ascanio to create a simple, robust and affordable vehicle. The motorcycle had to be easy to drive for both men and women, be able to carry a passenger, and not get its driver's clothes dirty. The engineer's drawings proved a significant departure from the Paperino. With the help of Mario D'Este he prepared the first Vespa project, manufactured at Piaggio newly-rebuilt Pontedera headquarters in April 1946. Piaggio launched the Vespa (Italian for "wasp") and within ten years more than a million units had been produced. The Italian language gained a new word, "vespare", meaning to go somewhere on a Vespa.

In 2024, Piaggio celebrated 140 years with limited edition of 'Vespa 140th of Piaggio,' with only 140 units available from April 18th to 21, 2024.

Ownership

Vespa thrived until 1992 when Giovanni Alberto Agnelli, son of Antonella Bechi Piaggio and Umberto Agnelli, became CEO. Agnelli was very successful in expanding production and modernising the offer. He died unexpectedly of cancer in 1997, aged 33. In 1999 Morgan Grenfell Private Equity acquired Piaggio, but hopes for a quick sale were dashed by a failed joint venture in China. In Italy, Piaggio invested 15 million euros in a new motorcycle but dropped it after building a prototype. By the end of 2002, the company had run up 577 million Euros in debt on revenues of 945 million Euros, and booked a loss of 129 million Euros.

In 2003 Piaggio's debt was reduced by a 100 million Euro investment made by IMMSI, a holding company of the Colaninno family. 150 million shares were also converted by creditor banks. Reflecting on his investment, Roberto Colaninno said,

"A lot of people told me I was crazy. Piaggio wasn't dying. It just needed to be treated better." "

Colaninno became the new chairman of Piaggio, and Rocco Sabelli the managing director. Sabelli redesigned the production line according to Japanese principles so that every Piaggio scooter could be made on any assembly line. Contrary to expectations, Colaninno did not sack a single worker; a move which helped seduce the company's skeptical unions. "Everyone in a company is part of the value chain," said Colaninno. All bonuses for blue-collar workers and management were based on the same criteria: profit margins and customer satisfaction. Air conditioning was installed in the factory for the first time, increasing productivity. He also gave the company's engineers, who had been idled by the company's financial crisis, deadlines for projects. They rolled out two world firsts in 2004: a gas-electric hybrid scooter and a sophisticated tilting scooter with two wheels in front and one in back to grip the road better.

One of Piaggio's problems Colaninno couldn't fix from the inside was its scale. Even though Piaggio was the European market leader, it was dwarfed by rivals Honda and Yamaha. A year after restoring Piaggio's health, Colaninno directed Piaggio's takeover of the Italian scooter and motorcycle manufacturer Aprilia, and with it the Aprilia-owned Moto Guzzi, a storied Italian manufacturer of motorcycles.

In 2006, Piaggio was floated on the Milan Stock Exchange, becoming a public company.

Production
In 1956, with production of the millionth Vespa scooter, Italy had its first mass-produced motorised vehicle. Taking advantage of increased cash flow thanks to the success of the Vespa, Piaggio developed other products, including the 1957 Vespa 400, a compact passenger car.

In 1959 Piaggio came under the control of the Agnelli family, the owners of car maker Fiat SpA.

By 1960 Vespa had produced and sold 4 million units worldwide.

In 1964 the aeronautical and motorcycle divisions of Piaggio split to become two independent companies as a result of the wide ownership by Fiat in Italian industry. The aeronautical division was named IAM Rinaldo Piaggio. The aircraft company Piaggio Aero was controlled by the family of Piero Ferrari, who still hold 10% of Ferrari.

In 1969 Piaggio purchased the motorcycle company Gilera, one of the oldest European motorcycle manufacturers (founded in 1909), famous for its sporting achievements and world titles in the Motorcycle World Championship.

In 1971 a steering wheel was added to the Piaggio Ape, a model first produced in 1948, culminating in the Ape Car. Four years later, in 1975, the company made the first prototype of an electric Ape.

In 1988 the Vespa reached 10 million units produced.

In 1996, on the fiftieth anniversary of the first model, Vespa passed 15 million units produced and the new 4-stroke Vespa ET, the first completely new Vespa for 18 years, was launched. Piaggio was still in poor financial health but its brand recognition remained strong, boosted by the appearance of the ET4 in several Hollywood films.

In 1999, in Baramati, production began on a three-wheeler Ape for the Indian market.

In 2000 Piaggio and Vespa returned to the United States with the opening of the first Vespa Boutique in Los Angeles. In that same year the Piaggio Historical Museum was inaugurated in Pontedera. The museum showcases the Piaggio Historical Archive, one of the most comprehensive company archives on the industrial history of Italy.

In 2001 the Piaggio Group acquired Derbi-Nacional Motor SA, an historical Spanish brand founded in 1922 that had won 18 world titles and was a continental leader in the small displacement motorbike segment. In the same year Gilera returned to the Motorcycle World Championship and immediately won the world title in the 125 category with Manuel Poggiali.

In April 2004 Piaggio and Chinese manufacturer Zongshen signed a memorandum of understanding for the creation of the “Zongshen Piaggio Foshan Motorcycle” joint venture with a plant in Foshan for the production of scooters for the Chinese market.

In 2004, at the end of December, the final contract for the acquisition of the Aprilia-Moto Guzzi Group was signed. The most important European two-wheeler group is born.

In 2007 Piaggio Group arrived in Vietnam. The Vinh Phuc plant includes R&D, welding and painting activities, as well as final assembly of the scooters, with warehouse, testing, quality control and office areas.

In 2009 the Piaggio Mp3 Hybrid made its debut on the market which was first hybrid scooter in the world, integrating the conventional low-environmental-impact internal combustion engine with a zero-emission electric motor and combining the advantages of the two power trains.

In Baramati (State of Maharashtra), in 2012, the Piaggio Group's new plant for the production of Vespa's for the local market was opened.

In 2013 the PADC, Piaggio Advanced Design Center opened in Pasadena (California, United States). The Vespa 946 was also launched this year, along with the new Vespa Primavera, the latest evolution of the "small body" family.

In 2013 Vespa's worldwide sales numbered almost 190,000 units; in 2004 the figure stood at 58,000. In ten years of continuous progression over 1.3 million new Vespas have been produced. Since 1946 over 18 million Vespas have been produced and sold.

In September 2017 Foton and Piaggio agreed to form a joint venture to develop and produce light commercial vehicle. Based on Foton chassis the new vehicle was sold by Piaggio Commercial Vehicle division globally apart from China. The vehicle is intended to be a successor of the Piaggio Porter and production was planned to start in mid-2019 in Pontedera (Italy) with all components produced by Foton in China.

"Cultural Project" Piaggio
Piaggio's "cultural project" promotes the reconstruction and enhancement of the company's heritage and is composed by three initiatives: the Piaggio Foundation, the Historical Archives and the Piaggio Museum. In 2003 the Museum and Archives were recognised as the Best Corporate Museum and Archive by winning the Italian prize "Premio Impresa e Cultura". In 2016, under the patronage of the Italian Ministry of Culture, Piaggio received the Corporate Art Award from pptArt for its Corporate Museum.

Group brands

 * Aprilia – motorcycles, scooter and mopeds
 * Piaggio – scooters, mopeds.
 * Vespa – scooters and mopeds
 * Scarabeo – scooters and mopeds
 * Derbi – motorcycles, scooters, mopeds and recreational ATVs (quads)
 * Gilera – motorcycles, scooters, mopeds and recreational ATVs (quads) 1909 – 2020
 * Laverda – motorcycles
 * Moto Guzzi – motorcycles
 * Piaggio Commercial Vehicles – light commercial vehicles

Current production
2-wheeled vehicles
 * Piaggio Fly (Asian market)
 * Piaggio Beverly
 * Piaggio Liberty
 * Piaggio Medley
 * Vespa
 * Piaggio Zip
 * Piaggio X7 (Asian market)
 * Piaggio 1

3-wheeled vehicles
 * Piaggio MP3
 * Piaggio Ape
 * Piaggio MyMoover

Commercial vehicles
 * Piaggio Porter

Discontinued
2-wheeled vehicles
 * Piaggio Boss
 * Piaggio Boxer
 * Piaggio Bravo
 * Piaggio Carnaby
 * Piaggio Ciao
 * Piaggio Cosa
 * Piaggio Diesis
 * Piaggio Free
 * Piaggio Grande
 * Piaggio Grillo
 * Piaggio Hexagon
 * Piaggio NRG
 * Piaggio Quartz
 * Piaggio Scatto
 * Piaggio Sfera
 * Piaggio Skipper
 * Piaggio Si
 * Piaggio Toledo
 * Piaggio Typhoon
 * Piaggio Vespino
 * Piaggio Velofax
 * Piaggio X7
 * Piaggio X8
 * Piaggio X9
 * Piaggio X10
 * Piaggio Xevo

3-wheeled vehicles
 * Piaggio Ciao Porter

Commercial vehicles
 * Piaggio Quargo

All-terrain vehicles
 * Piaggio Trackmaster (rebadged Arctic Cat TRV)

Quadricycles
 * Piaggio M500 (rebadged Casalini Ydea)
 * Piaggio AL500 (rebadged Grecav Eke)
 * Piaggio PK500 (rebadged Grecav Eke Pick-up)

Aircraft engines (1920-1950)
 * Piaggio P.VI
 * Piaggio P.VII
 * Piaggio P.VIII
 * Piaggio P.IX
 * Piaggio P.X
 * Piaggio P.XI
 * Piaggio P.XII
 * Piaggio P.XV

Electric scooters
The new plug-in hybrid version of the Piaggio MP3 will be equipped with a 125 cc petrol engine and electric motor, which offers about 141 mpgus and travels 13 mi using battery power alone. This machine could be out in 2009.

Piaggio/Vespa are also developing hybrid electric scooters. There are two models in the works, based on the popular Vespa LX 50 and the beefier Piaggio X8 125.

At the Beijing Motor Show 2021, Piaggio unveiled the brand new electric scooter Piaggio 1. This model was produced in three versione: 1 base, 1+ and 1 Active. The 1 base has a 1.4 kWh and 48V battery, a 1.2 kW engine, a torque of 85 Nm, a maximum speed of 45 km/h (it is therefore approved as a moped) and a range of 55 km. The 1+ version differs in the battery that rises to 2.3 kWh and the autonomy that reaches 100 kilometers. The 1 Active model has the same 2.3 kWh battery, but the engine has a maximum power of 2 kW, the torque goes to 95 Nm and the speed rises to 60 km/h (motorcycle homologation), the average range is 85 km. For all versions the charging times are 6 hours.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Piaggio


text:
Ferdinand I of the Two Sicilies

Ferdinand I (12 January 1751 – 4 January 1825) was King of the Two Sicilies from 1816 until his death. Before that he had been, since 1759, King of Naples as Ferdinand IV and King of Sicily as Ferdinand III. He was deposed twice from the throne of Naples: once by the revolutionary Parthenopean Republic for six months in 1799, and again by a French invasion in 1806, before being restored in 1815 at the end of the Napoleonic Wars.

Ferdinand was born in Naples as the third son of King Charles VII and Queen Maria Amalia. In August 1759, Charles succeeded his half-brother Ferdinand VI of Spain as King Charles III, but treaty provisions made him ineligible to hold all three crowns. On 6 October, he abdicated his Neapolitan and Sicilian titles in favour of his third son, Ferdinand, because his eldest son Philip had been excluded from succession due to intellectual disability and his second son Charles was heir-apparent to the Spanish throne. Ferdinand was the founder of the cadet House of Bourbon-Two Sicilies.

Childhood
Ferdinand was born in Naples and grew up amidst many of the monuments erected there by his father which can be seen today; the Palaces of Portici, Caserta and Capodimonte.

Ferdinand was his parents' third son; his elder brother Charles was expected to inherit Naples and Sicily. When his father ascended the Spanish throne in 1759, he abdicated the thrones of Naples and Sicily in Ferdinand's favour in accordance with the treaties forbidding the union of the two crowns. A regency council presided over by the Tuscan Bernardo Tanucci was set up. Tanucci, an able, ambitious man, wishing to keep the government as much as possible in his own hands, purposely neglected the young king's education, and encouraged him in his love of pleasure, his idleness and his excessive devotion to outdoor sports.

Reign
Ferdinand's minority/childhood ended in 1767, and his first act was the expulsion of the Jesuits. The following year he married Archduchess Maria Carolina, daughter of Empress Maria Theresa. By the marriage contract, the queen was to have a voice in the council of state after the birth of her first son, and she was not slow to avail herself of this means of political influence.

Tanucci, who attempted to thwart her, was dismissed in 1777. The Englishman Sir John Acton, who in 1779 was appointed director of marine, won Maria Carolina's favour by supporting her scheme to free Naples from Spanish influence, securing rapprochement with the Archduchy of Austria and the Kingdom of Great Britain. He became practically and afterward actually prime minister. Although not a mere grasping adventurer, he was largely responsible for reducing the internal administration of the country to a system of espionage, corruption and cruelty.

French occupation and the Parthenopaean Republic
Although peace was made with France in 1796, the demands of the French Directory, whose troops occupied Rome, alarmed Ferdinand once more. At his wife's instigation, he took advantage of Napoleon's absence in the French campaign in Egypt and Syria and of Horatio Nelson's victories to go to war. Ferdinand marched with his army against the French and entered Rome (29 November). On the defeat of some of his columns, Ferdinand hurried back to Naples. On the approach of the French, Ferdinand fled on 23 December 1798 aboard Nelson's ship HMS Vanguard (1787) to Palermo, leaving his capital in a state of anarchy. The weather was extremely stormy and the king's 6-year-old younger son Prince Alberto died of exhaustion during the voyage, in the arms of Emma, Lady Hamilton, Nelson's mistress.

The French entered the city despite the fierce resistance of the lazzaroni, and with the aid of the nobles and bourgeoisie, established the Parthenopean Republic in January 1799. A few weeks later, when the French troops were recalled to northern Italy, Ferdinand sent a hastily assembled force under Fabrizio Cardinal Ruffo to reconquer the mainland kingdom. Ruffo, with the support of British artillery, the Church, and the pro-Bourbon aristocracy, succeeded in reaching Naples in May 1800, and the Parthenopean Republic collapsed. After some months, King Ferdinand returned to the throne.

The king and the queen were anxious that no mercy should be shown to the rebels, and Maria Carolina (a sister of the executed Marie Antoinette) made use of Lady Hamilton to induce Nelson to carry out her vengeance.

Third Coalition
The king returned to Naples soon afterwards, and ordered the execution of a few hundred French collaborators. This stopped only when the French successes forced him to agree to a treaty which included amnesty for members of the French party. When the War of the Third Coalition broke out between France and the Austrian Empire in 1805, Ferdinand signed a treaty of neutrality with the former. A few days later, Ferdinand allied himself with Austria and allowed an Anglo-Russian force to land at Naples.

The French victory at the Battle of Austerlitz on 2 December enabled Napoleon to launch an invasion of the Kingdom of Naples. Ferdinand fled to Palermo on 23 January 1806, followed soon after by his wife and son, and on 14 February 1806 the French again entered Naples. Napoleon declared that the Bourbon dynasty had forfeited the crown, and proclaimed his brother Joseph King of Naples and Sicily. But Ferdinand continued to reign over the latter kingdom (becoming the first King of Sicily in centuries to actually reside there) under British protection.

Parliamentary institutions of a feudal type had long existed on the island, and Lord William Bentinck, the British minister, insisted on a reform of the constitution on English and French lines. The king indeed practically abdicated his power, appointing his son Francis as regent, and the queen, at Bentinck's insistence, was exiled to Austria, where she died in 1814.

Restoration

After the fall of Napoleon, Joachim Murat, who had succeeded Joseph Bonaparte as king of Naples in 1808, was dethroned in the Neapolitan War in 1815, and Ferdinand returned to Naples. By a secret treaty he had bound himself not to advance further in a constitutional direction than Austria should at any time approve; but, though on the whole he acted in accordance with Metternich's policy of preserving the status quo, and maintained with but slight change Murat's laws and administrative system. Ferdinand took advantage of the situation to abolish the Sicilian constitution, in violation of his oath, and to proclaim the union of the two states into the Kingdom of the Two Sicilies (12 December 1816).

Ferdinand was now completely subservient to Austria, an Austrian, Count Nugent, being even made commander-in-chief of the army. For the next four years, Ferdinand reigned as an absolute monarch within his domain, granting no constitutional reforms.

1820 revolution

The suppression of liberal opinion caused an alarming spread of the influence and activity of the secret society of the Carbonari, which in time affected a large part of the army. In July 1820, a military revolt broke out under General Guglielmo Pepe, and Ferdinand was terrorised into signing a constitution on the model of the Spanish Constitution of 1812. On the other hand, a revolt in Sicily, in favour of the recovery of its independence, was suppressed by Neapolitan troops.

The success of the military revolution at Naples seriously alarmed the powers of the Holy Alliance, who feared that it might spread to other Italian states and so lead to a general European conflagration. The Troppau Protocol of 1820 was signed by Austria, Prussia and Russia, although an invitation to Ferdinand to attend the adjourned Congress of Laibach (1821) was issued at which he failed to distinguish himself. He had twice sworn to maintain the new constitution but was hardly out of Naples before he repudiated his oaths and, in letters addressed to all the sovereigns of Europe, declared his acts to have been null and void. Metternich had no difficulty in persuading the king to allow an Austrian army to march into Naples "to restore order".

The Neapolitans, commanded by General Pepe, made no attempt to defend the difficult defiles of the Abruzzi, and were defeated at Battle of Rieti (7 March 1821). The Austrians entered Naples.

Later years
Following the Austrian victory, the Parliament was dismissed and Ferdinand suppressed the Liberals and Carbonari. The victory was used by Austria to force its grasp over Naples' domestic and foreign policies. Count Charles-Louis de Ficquelmont was appointed as the Austrian ambassador to Naples, practically administering the country as well as managing the occupation and strengthening Austrian influence over Neapolitan elites.

Ferdinand died in Naples on 4 January 1825. He was the last surviving child of Charles III.

Cultural depictions

 * That Hamilton Woman (1941) directed by Alexander Korda, played by Luis Alberni
 * Ferdinando and Carolina (1999) directed by Lina Wertmüller, played by Sergio Assisi, Adriano Pantaleo, and Mario Scaccia at different ages
 * Luisa Sanfelice (2004) directed by Paolo and Vittorio Taviani, played by Emilio Solfrizzi

title: Ferdinand I of the Two Sicilies


text:
Vespa 400

The Vespa 400 is a rear-engined microcar, produced by ACMA in Fourchambault, France, from 1957 until 1961 to the designs of the Italian Piaggio company. Three different versions were sold, the "Luxe", "Tourisme" and "GT".

Overview
The car made its high-profile public debut on 26 September 1957 at a press presentation staged in Monaco. The ACMA directors ensured a good attendance from members of the press by also inviting three celebrity racing drivers to the Vespa 400 launch.

The 400 was a two seater with room behind the seats to accommodate luggage or two small children on an optional cushion. The front seats were simple tubular metal frames with cloth upholstery on elastic "springs" and between the seats were the handbrake, starter and choke. The gear change was centrally floor mounted. The rear hinged doors were coated on the inside with only a thin plastic lining attached to the metal door panel skin allowing valuable extra internal space. On the early cars the main door windows did not open which attracted criticism, but increased the usable width for the driver and passenger. Instrumentation was very basic with only a speedometer and warning lights for low fuel, main beam, dynamo charging and indicators. The cabriolet fabric roof could be rolled back from the windscreen header rail to the top of the rear engine cover leaving conventional metal sides above the doors. The 12-volt battery was located at the front of the car, behind the dummy front grill, on a shelf that could be slid out. The spare wheel was stowed in a well under the passenger seat.

Marketing
The high-profile launch paid off, with 12,130 cars produced in 1958. That turned out to be the high point, however, and output fell to 8,717 in 1959 despite a price reduction for the entry level 2-seater "normal" coupé from 345,000 francs to 319,500 francs between October 1957 and October 1958. Commentators suggested that the chic image created at the time of the launch was not always matched by the car itself, with its awkward gear change, poor sound-proofing and, especially before a modification to the carburetor specification, high fuel consumption. The car's origins, developed by a leading world producer of motor scooters, Italy's Piaggio Company, makers of the Vespa since 1946, was reflected in the installation, in the Vespa 400, of a two stroke (motorbike style) engine which required oil to be added to the petrol/gasoline whenever the car was refueled. During the summer of 1958 the cars were fitted with a semi-automatic device for adding oil to the fuel, but a fully automatic fuel mixing device was not included until two years later.

Road test

The British Motor magazine tested a 400 de luxe saloon in 1959 recording a top speed of 51.8 mph and acceleration from 0-40 mph in 23.0 seconds and a fuel consumption of 55.3 mpgimp. The test car cost 351,725 "old" French Francs, cheaper than the 374,000 "old" French Francs domestic market starting price quoted towards the end of 1958 for the cheapest version of the larger but (even) less powerful Citroën 2CV.

Specifications

 * Engine: Two cylinder, two-stroke, air-cooled. Bore and stroke: 63 mm x 63 mm (393 cc). Motor cyclists at the time were used to mixing oil into their fuel, but the manufacturer belatedly realised that this might compromise the 400's standing as a "car", and from the summer of 1958 the two-stroke oil was held in separate reservoir with a semi-automatic dispenser on the right side of the engine bay.
 * Compression ratio: 6.4:1 with 13 hp, later increased respectively to 6.6:1 and 14 hp.

 * Suspension: Four wheel independent. Four double acting hydraulic shock absorbers with coil springs. Front anti-roll bar.
 * Manual transmission: 3 speed plus reverse, with 2nd & 3rd synchromesh. 4 speed available only in Europe markets.
 * Brakes: Hydraulically operated drums of 6.75 in diameter.

 * Performance:With only 14 hp (10 kW), top speed is 50 to 55 mph (80 to 90 km/h), depending on road grade, wind conditions, etc. Achieving top speed takes 25 seconds. Fuel economy is about 5 L/100 km.

title: Vespa 400


text:
Talk:O Brother, Where Art Thou?

Pete's Surname
I notice that in the plot summary, no surname is given for Pete, but in the cast list, his surname is listed as "Hogwallop." It is unclear from the movie whether Pete's surname is Hogwallop; it is only certain that Hogwallop is the surname of Cousin Wash. After Pete's betrayal, he says, "Must be my Hogwallop blood," but he also says that his father told him, "Never trust a Hogwallop," something that seems unlikely if it is Pete's (and therefore his father's) surname. Should Hogwallop be removed as Pete's surname in the cast list? SpankyMac (talk) 22:07, 13 January 2009 (UTC)

I went ahead and made this change. SpankyMac (talk) 01:56, 15 January 2009 (UTC)

I thought I had made this change back in January, but either I was mistaken or it was reverted. Is there any valid argument for listing Pete's surname as Hogwallop? If there's credible information to support this, I am happy to refrain, but it seems clear to me that Pete's surname is not established anywhere in the film or in the film's credits.--SpankyMac (talk) 23:35, 22 July 2009 (UTC)
 * Per this G-search, it appears that many reviewers tend to attribute that last name to Pete. Additionally, that search shows that several cast lists give him that last name as well. Is this enough, in your view, to justify keeping it in the article? As a huge fan of the movie, I'd never really questioned that Hogwallop was his last name. I have always simply attributed the "never trust a Hogwallop" quote to the anachronistic nature of the movie. Unitanode  15:08, 24 July 2009 (UTC)
 * It's absolutely true that plenty of people take for granted that Pete's last name is Hogwallop, but in the cast lists from IMDB and similar sites, he's only listed as "Pete." I'm not sure how the movie's anachronistic nature would make sense of the "never trust a Hogwallop" line, which makes much more sense to me if Pete's Ma is Wash's Pa's sister, which would account for Pete's Pa's distrust of his in-laws and also Pete's "Hogwallop blood," in addition to strongly implying that Pete's surname is something OTHER than Hogwallop.  My main contention, though, is that there's no unqualified evidence within the movie itself just what Pete's surname actually is. --SpankyMac (talk) 11:30, 30 July 2009 (UTC)

I'm changing it back, and if anyone objects, I'm delighted to debate it further.--SpankyMac (talk) 17:32, 1 August 2009 (UTC)
 * I really don't have much of a problem with this at all. I just watched the movie again, and I'm still of the opinion that the whole "never trust a Hogwallop" is simply irony, but it's not so important as to argue about really. Unitanode  20:20, 1 August 2009 (UTC)

It's easy enough to edit the text to reflect the possibility that he's named Hogwallop, and I will do so. As for cast lists, the one at IMDB doesn't give anyone's last name but it's clear they have full names. My take as a viewer (and I'm watching the movie now) is that he implies it's his family but that yes, it's ambiguous. Dig the edit.--Pergish1 (talk) 02:15, 7 February 2010 (UTC)

I don't dig the edit. I realize that I'm fighting a losing battle here, since someone always comes back and undoes my edit, but the current change doesn't reflect ambiguity, but rather comes down rather firmly on the "Pete Hogwallop" side. People change it back to Hogwallop just because they want it to be Hogwallop, not because there's any real indication that that's what his name is. The movie does not assign Pete a surname, so this article should not, either. Show me an interview with the Coens in which they identify him as Hogwallop, and I'll leave it alone, but it's pretty clear from the context that Pete's Ma had been the Hogwallop in the family, rather than Pete's Pa. I expect to revert this to my previous wording within the next few days. SpankyMac (talk) 03:15, 11 January 2011 (UTC)
 * You're absolutely correct. Pete's last name is never given in the film, but it's stated that he's related to the Hogwallops. The relevant info is:
 * Wash Hogwallop is Pete's cousin. True, this could mean a cousin-once-removed or an even more distant cousin, but to keep things simple (Occam's razor!) we should assume that they're first cousins. Anyway, as Pete says, "Wash is kin!", which is corroborated by Wash: "Sorry Pete, I know we're kin, but ..."
 * Pete: "Pa always said: Never trust a Hogwallop!" - Which only makes sense when Pete's father isn't/wasn't a Hogwallop himself.
 * Pete, reflecting on his supposed treason: "Must be my Hogwallop blood." - Which only makes sense if his "Hogwallop blood" is secondary to his "main family blood". So this quote alone proves that he is a Hogwallop on his mother's side.
 * There's even more known family members, one Cousin Vester (who hanged himself a year come May) and one Uncle Ratliff (who lost most of his cows to anthrax and a boy to mumps). I suppose they're from Pete's mother's side too, since he probably would ask Wash about their shared kin, not about some people Wash isn't related to; but the exact relationship is unclear ("Ratliff" might even be a surname).
 * To clarify, here's the family tree (the branches of Pete and Wash are pretty certain, while the branches of Cousin Vester and Uncle Ratliff should be taken with a grain of salt):

┌───────────────┐                                      │NN Hogwallop   │ │source of the │ │Hogwallop blood│ └───────┬───────┘                                    ┌─────────┴────────┬──────────────────────────────────────────────────┬────────────────────────┐ ┌────────────────────────┐   ┌──────┴──────┐    ┌──────┴──────┐   ┌──────┐                       ┌────────┴─────────┐   ┌──────────┴─────────┐ │Pete's father, who never│ ∞ │Pete's mother│    │NN Hogwallop │ ∞ │Wash's│                       │   NN Hogwallop   │   │Uncle Ratliff, whose│ │trusted a Hogwallop    │ │ │née Hogwallop│    │Wash's father│ │ │mother│                       │                  │   │cows don't milk     │ └────────────────────────┘ │ └─────────────┘   └─────────────┘ │ └──────┘                       └────────┬─────────┘   └──────────┬─────────┘                            │                                    │                                         │                        │                        ┌───┴────┐      ┌────────────────────────┴───────┐   ┌────────────────┐   ┌────────┴─────────┐   ┌──────────┴─────────┐                        │  Pete  │      │Washington Bartholomew Hogwallop│ ∞ │Cora, who r-u-n-│   │Cousin Vester, who│   │    Boy who died    │ │       │      │aka "Cousin Wash"               │ │ │n-o-f-t, looking│   │was foreclosed and│   │    from mumps      │ └────────┘     │aka "Judas Iscariot Hogwallop"  │ │ │for answers     │   │hanged himself    │   └────────────────────┘ └────────────────────────────────┘ │ └────────────────┘  └──────────────────┘                                                                           │                                                                   ┌───────┴──────┐                                                                   │Boy who nicked│ │the census man│ └──────────────┘
 * Greetings, Tilberg (talk) 19:28, 29 January 2020 (UTC)

Down By Law
Does anyone else notice the plot similarities between this film and Jim Jurmusch's great Down By Law? Subcrop 22:13, 11 October 2007 (UTC)

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Tommy Johnson Character
This article, I believe is incorrect in its ascertaining that Tommy Johnson is based on Robert Johnson. Tommy Johnson (no relation to Robert) was the first to have the story of the crossroads told about him. Tommy was a blues guitarist and his biggest hit was "Canned Heat Blues" because he was such a bad alcoholic that he would get cans of sterno and drink the liquid fuel in the cans. That's what the song's about. There are many who say Robert only told people about his 'deal with the devil' because he had heard of Tommy Johnson's "deal" and thought the talk of it might be sensational and help his career.

As an aside, in a different movie - Crossroads, starring Ralph Macchio and Joe Seneca, a secondary character in a juke joint is called "Lydale", which ironically was Tommy Johnson's brother and a minister who told everyone about his brother's deal with the devil. Lydale is the creator of this folklore.

I would like to change the bullet point about Tommy Johnson's role to reflect true history.

mhaize george melton — Preceding unsigned comment added by Mhaize (talk • contribs) 04:51, 24 August 2016 (UTC)

Production companies and distributors
, if you have a source for these production companies and distributors, you can add them back. However, the American Film Institute says that Working Title Films is the sole production company. The distributors are unsourced besides what AFI listed. Per WP:BURDEN, please do not re-add this unsourced content until you properly source it. Keep in mind that the IMDb is user-generated content and not a reliable source. NinjaRobotPirate (talk) 14:22, 25 October 2016 (UTC)

 * That will not be necessary for I've quickly withdrew my support for this article and the film itself. — FilmandTVFan28 (talk) 18:43, 25 October 2016 (UTC)

Tommy Johnson
The description for Tommy Johnson has two links to the same page. Wolf O'Donnel (talk) 17:31, 12 February 2017 (UTC)
 * You are correct. I apologize for implying you were vandalizing. ---  The Old Jacobite   The '45  19:04, 12 February 2017 (UTC)

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1937 setting and Baby Face Nelson
Is the setting really 1937? The film has Baby Face Nelson in it, who died in 1934. Is this artistic muddling of facts or is the claimed 1937 setting wrong? ADDING 50 years to an existing sentence does not equal 50. So 1937 can not be the year. — Preceding unsigned comment added by 2003:ED:2724:C010:EC5C:E954:2491:F1A5 (talk) 04:30, 30 June 2024 (UTC)
 * See several film errors here: https://www.imdb.com/title/tt0190590/goofs — Preceding unsigned comment added by 70.161.8.90 (talk) 00:35, 26 May 2021 (UTC)
 * Pete says he only had a few weeks until release, but his escape would add fifty years to his sentence, which would mean he wouldn't get out until 1987, so 1937 seems like the year. Nelson died in a police shootout anyway; his character is kind of fictionalized. Bkatcher (talk) 21:14, 23 March 2022 (UTC)

Soundtrack
The article says:

“… the soundtrack won a Grammy Award for Album of the Year in 2002, making it the only motion picture soundtrack to have ever received the accolade.”

Is this accurate? Didn’t Saturday Night Fever and The Bodyguard also both win Album of the Year? 75.147.166.213 (talk) 15:25, 12 June 2022 (UTC)
 * You are correct. Go ahead and change it with a cite showing that all three albums won the award.  Good catch!  Sir Rhosis (talk) 15:40, 12 June 2022 (UTC)

References to "The Odyssey"
I'm new to editing Wikipedia articles! And for one of my classes, it is required to edit one article! I love this film and have loved it for some time. I thought it would be a easy edit to add a few similarities between "O Brother" and Homer's "The Odyssey". For example, both the film and the poem have a Cyclops, or at least a Cyclops-like figure, both have Sirens, and both have the same basic storyline and ending. Any feedback would be appreciated! Thank you! Droopykitten612 (talk) 18:53, 2 December 2022 (UTC)

Sheriff Cooley devil
I think it is *strongly* implied that Sheriff Cooley is the incarnation of the devil, but I’m not sure if that should be stated in the cast section. Qbox673 (talk) 05:25, 7 January 2023 (UTC)

title: Talk:O Brother, Where Art Thou?


text:
Bang

Bang or bangs may refer to:

Products

 * M1922 Bang rifle, a US semi-automatic rifle designed by Søren Hansen Bang
 * Bang, a model car brand
 * Bang (beverage), an energy drink

Geography

 * Bang, Central African Republic
 * Bang, Lorestan, a village in Iran
 * Bangs, Ohio, United States
 * Bangs, Texas, United States

People

 * Bang (surname)
 * Bangs (surname)
 * Bang, pseudonym of Barbro Alving (1909-1987), Swedish journalist
 * Stage name for Bae "Bang" Jun-sik, professional League of Legends player for Evil Geniuses

Print media

 * Bang!, a 2005 young adult novel by Sharon G. Flake
 * Bang: The Pickup Bible That Helps You Get More Lays, a 2007 book by Roosh V
 * Bang, a character in the manga series One-Punch Man
 * Bay Area News Group (BANG), the largest newspaper publisher in the San Francisco Bay Area

Magazines

 * Bang (magazine), founded 1991, Swedish magazine
 * The Bang (Vagabonds), 1907-1917, the weekly magazine of the Vagabonds (National Arts Club)

Film and television

 * Bang (TV series), a bilingual crime drama TV series from Wales
 * Bang (film), a 1997 American film
 * Bang! (film), a 1977 Swedish film
 * "Bang" (Daredevil)
 * "Bang" (Desperate Housewives)
 * "Bang" (The Good Wife)
 * "Bang" (Harper's Island)
 * "Bang" (The Shield)
 * "Bangs", an episode of "The Protector"
 * Bang Cartoon, a website

Games

 * Bang! (card game)
 * Bang! (arcade game)
 * Bang! (drama game), a game involving imaginary guns
 * Bang! (video game)
 * Bang Shishigami, a BlazBlue character

Music

 * Bang! (opera), by John Rutter
 * Bang Records, a record label
 * Bang! Records, a record label
 * Bang (company), a music and sound production company from NYC

Groups and musicians

 * Bang (Greek band), a Greek pop music group
 * Bang (American band), an American hard rock group
 * Bang! (band), a British happy hardcore group
 * Bangs (band), an American punk rock group
 * Bangs (hip hop artist) (born 1992), South Sudanese-Australian hip hop artist
 * Bang, former bass player for Stars Underground and Astrovamps

Albums

 * Bang! (1985 Frankie Goes to Hollywood album)
 * Bang (Anitta album), 2015
 * Bang (Chief Keef album), 2011
 * Bang (James Gang album), 1973
 * Bang (The Jesus Lizard album), 2000
 * Bang (Rockapella album), 2002
 * Bang! (Cinema Bizarre album), 2009
 * Bang! (Corey Hart album), 1990
 * Bang! (Gotthard album) and its title track, 2014
 * Bang! (Thunder album), 2008
 * Bang! (World Party album), 1993
 * Bang!... The Greatest Hits of Frankie Goes to Hollywood, 1993

EPs

 * Bang (Rita Ora and Imanbek EP), 2021
 * Bang, 2007 EP by Nightmare of You
 * Bang! (EP), 1997 EP by the Goo Goo Dolls

Songs

 * "Bang" (Anitta song), 2015
 * "Bang" (Blur song), 1991
 * "Bang" (Gorky Park song), 1989
 * "Bang" (Rye Rye song), featuring M.I.A.,
 * "Bang!" (After School song), 2011
 * "Bang!" (AJR song), 2020
 * Bang (Conway the Machine song), 2019
 * "Bang", a song by Waka Flocka Flame featuring YG Hootie & Slim Dunkin on the album Flockaveli
 * "Bang", a song by Dave Dee, Dozy, Beaky, Mick & Tich from the album If Music Be the Food of Love... Prepare for Indigestion
 * "Bang", a song by Yeah Yeah Yeahs from the EP Yeah Yeah Yeahs
 * "Bang", a song by Badmarsh & Shri from the album Signs
 * "Bang!", a song by The Raveonettes from the album In and Out of Control
 * "Bangs", a song by They Might Be Giants on the album Mink Car

Other uses

 * !Bang, a search syntax used by search engine DuckDuckGo
 * !Bang!, a professional wrestling promotion
 * Bang (Korean), a room or building
 * Bangs (hair), the part of the hair overhanging the forehead
 * Bang's disease
 * Exclamation mark (!), a punctuation symbol sometimes called a "bang"
 * Interrobang (‽), a nonstandard punctuation mark intended to combine the functions of the question mark and the exclamation mark (the latter is known in printers' and programmers' jargon as a "bang")
 * shebang (Unix), the  character sequence used to specify an interpreter for a computer program

 * An onomatopoeia, specifically a word that imitates the sound of an explosion or gunshot, like in comics
 * Slang for an explosion
 * Slang for "to have sex with"
 * Slang for flash-bang

title: Bang


text:
Talk:Phong reflection model

Definition of L in Phong equation
Shouldn't L be the vector from the point on the surface to the light source? All other sources I have seen on this equation define it as such. —The preceding unsigned comment was added by 24.42.196.192 (talk • contribs) 21:34, 3 December 2004 (UTC)

 * Right, that got fixed shortly after your comment. Dicklyon 02:24, 30 May 2006 (UTC)

This a very interesting article! ^_^ —The preceding unsigned comment was added by 70.17.37.126 (talk • contribs) 19:24, 30 April 2006 (UTC)

 * Please sign your comments with four tildes as the editing talk page suggests. Dicklyon 02:24, 30 May 2006 (UTC)

Equation
Shouldn't the equation be Color * Diffuse + specular and NOT Color + Diffuse + Specular? Starfox 23:40, 25 July 2006 (UTC)

 * which equation are you referring to? Dicklyon 07:00, 26 July 2006 (UTC)

 * Perhaps the confusion is the ambient term? $$k_a$$ is the ambient colour, $$k_d$$ and $$k_s$$ are diffuse and specular. There are actually three different colour terms, each making a contribution to the lighting. Neither of the formulae you suggest represent what is currently on the page, or proper Phong lighting, though the specular colour is often very close to white, which may be why you have omitted its multiplication by colour in your suggestion. - Rainwarrior 07:28, 26 July 2006 (UTC)

 * Ah, I see it. The confusion is the picture diagrams below where the diffuse colour has been combined with the ambient colour. The "diffuse" picture should have colour to it, and the "ambient" picture should be much darker. I'll see if I can fix it. - Rainwarrior 07:31, 26 July 2006 (UTC)

 * Oh, right, the funny picture equation. It's not well explained, but if you interpret the text below it, where it explains that it's a gray object in a blue ambient environment, I think you'll find that it's not incorrect.  It could certainly be improved, though. Dicklyon 07:39, 26 July 2006 (UTC)

 * Ah, didn't spot that. Well, I edited the image as best I could to be a more traditional example where the diffuse and ambient colours are the same. - Rainwarrior 08:03, 26 July 2006 (UTC)

 * I don't think they add up to the left-hand image now. Maybe we should contact the guy who did it in the first place to do it over better. He probably has a programmable way to do it.  Or write one, using a new object, maybe even with more than one color. Dicklyon 19:12, 26 July 2006 (UTC)

 * Yeah, I couldn't get the colours quite right (my graphics editor didn't have the right controls for colour, I tried to approximate). I could rig up a demonstration program and redo it later. - Rainwarrior 21:21, 26 July 2006 (UTC)

 * I think I might be able to provide some pics on the classic teapot. I can do a simple GLSL shader in RenderMonkey. Interested? Starfox 23:02, 26 July 2006 (UTC)

 * Sure, go for it. - Rainwarrior 23:20, 26 July 2006 (UTC)

 * I can redo the image with the correct idea and more than one color, thanks for the corrections. - T-tus

I don't know if Starfox is still planning to do this or not, but I wrote a little software renderer and made a new image out of it. Looking at it now, I wish I'd used a more curved surface like the original version so there'd be more interesting specular highlights, but for now this at least is accurate, colour wise. - Rainwarrior 04:16, 7 August 2006 (UTC)

 * I hacked my raytracer to do some sort of ray-blob intersection (it was surprisingly tricky...), and made a new version of the image using a much curvier (and more specular) model. - Rainwarrior 18:09, 7 August 2006 (UTC

I think that must be R * L instead R * V in specular part of formula? —Preceding unsigned comment added by 87.116.153.207 (talk) 14:22, 28 November 2007 (UTC) My mistake, formula is correct, but somwhere should be 'R is feflected ray form LIGHT source'.

Phong shading
See talk:Phong shading for why we are keeping these as two separate pages, and what we are trying to do to make it work better. Dicklyon 17:13, 30 May 2006 (UTC)

Merge
I'm suggesting that we merge this article with Phong shading. While these articles cover two distinct topics, there is a great deal of ambiguity in the specific names for these things in real-world uses. The reflection model is very frequently referred to as a "shading model" (especially in this era of programmable shaders), or sometimes just "shading" or "lighting". I don't think the way we've separated them is appropriate, as the names really aren't so distinct in practice. The concepts are, but not the names. Neither of these articles is particularly long, and I don't think they have a great deal of potential for expansion. I think it would be best to merge the two, perhaps under "phong shading" with appropriate redirects, and clearly explain both the ambiguity of the naming of these two concepts, and the distinction between them. It gives us a good opportunity to explain their relationship as well. - Rainwarrior 03:46, 1 September 2007 (UTC)

 * I'm OK with such a merge. Merge this one into Phong shading? Dicklyon 04:45, 1 September 2007 (UTC)

 * Done. - Rainwarrior (talk) 21:25, 16 December 2007 (UTC)

As I commented on Phong shading, I think it would be better practice to properly restructure Shading and branch out along the two definitions instead of getting caught up in a giant semantic web. -- Danukasan (talk) 19:36, 13 April 2009 (UTC)

 * After a discussion on the talk page of Phong shading, it was decided to split the page again into Phong shading and Phong reflection model. This reflects today's usage in scientific literature and textbooks and it allows other articles (in particular articles on Wikipedia in other languages) to unambigiuously refer to one of the two concepts. --Martin Kraus (talk) 12:41, 7 June 2011 (UTC)

Computational approximations not relevant
The Phong reflection model doesn't say anything about how the intensity should be calculated; it is after all just a mathematical model. If the approximations would have simplified the mathematical expression in any way in order to make it easier to work with, they would have belonged here, but that is not the case now. I therefore consider them irrelevant to this article and will remove them again. --Kri (talk) 21:42, 7 June 2011 (UTC)

 * I disagree in so far as the Phong reflection model is mainly designed for efficient computation. If there wasn't an efficient computation of it, it would not be of interest. In fact, Phong wouldn't even have proposed it. The model is not designed to allow for a particularly short mathematical description or to accurately simulate reflection on physical surfaces but for efficient computation. Therefore, simplifications of the computation of the model are relevant. For the same reason, the Blinn-Phong reflection model is of interest in computer graphics. --Martin Kraus (talk) 23:08, 7 June 2011 (UTC)

 * I thought that the main reason for splitting up the article was that the reflection model didn't really have anything to do with Phong shading (except from that they are most often used together)? Covering different approximation methods in this article seems like taking a step towards bringing the two articles together again.

 * No, covering an approximation method for the Phong reflection model in this article does not bring it closer to the article of Phong shading (which is now about a specific interpolation method). Neither would an approximation of Phong shading (e.g. not normalizing normal vectors at vertices before they are linearly interpolated) bring the article about Phong shading closer to the article about the Phong reflection model. --Martin Kraus (talk) 08:04, 8 June 2011 (UTC)

 * I see it like this: Either we treat Phong shading and the Phong reflection model in one article, or we keep them separated, consider the reflection model as something that doesn't really have anything to do with Phong shading and don't cover anything in the article about the reflection model that has anything to do with computation; maybe it was good as it was when they were both in one article. I can't stop you from bringing the section back again, or doing anything else, if you think that is good, but at least I have left my thoughts about the question. --Kri (talk) 00:04, 8 June 2011 (UTC)

 * Phong shading (the interpolation method) is one method for computing the interpolation when shading. The Phong reflection model is one method for computing lighting when shading. Both are linked to computation. --Martin Kraus (talk) 08:04, 8 June 2011 (UTC)

 * I think you misunderstand the term "shading" in the term "Phong shading". Usually, Phong shading does not refer to an implementation of Phong's techniques but to a specific way of normal-vector interpolation. Phong shading is one interpolation technique. Flat shading and Gouraud shading are others. All of them can be combined with other reflection models: Phong reflection model is one of them. Toon or cell shading is another reflection model (where "shading" is used in another meaning). I guess the greatest confusion stems from the term shading, which can be used in the sense of lighting, interpolation of lighting, computation of pixel colors, computation of vertex colors, etc. However, in combination with other terms (e.g. Phong shading) it often has specific meanings. --Martin Kraus (talk) 08:04, 8 June 2011 (UTC)

 * Maybe we should just keep them as one article but include a section that discusses the difference between the two things; we have already started to argue about which sections should belong to which articles. Anyway, it's difficult to know what the best solution is. --Kri (talk) 00:12, 8 June 2011 (UTC)

 * Again, I would argue that the normal use of Phong shading in academia today is only to refer to the normal-vector interpolation (a method for computing the interpolation) and the Phong reflection model is about the lighting model (a method for computing the lighting). I'll add a reference to "Computer Graphics Principles" by Foley, van Dam, Feiner and Hughes to clarify this. I've added a couple of references to Phong shading to clarify this. --Martin Kraus (talk) 09:25, 8 June 2011 (UTC)

 * I also understood Phong shading as something that is not necessarily connected to the Phong reflection model. You said that the Phong shading article is now about a specific interpolation method; do you think something is missing in the article?

 * No, sorry, I only wanted to clarify that - as you said - it doesn't necessarily include the Phong reflection model and therefore an approximation of the Phong reflection model shouldn't be in the article about Phong shading. --Martin Kraus (talk) 11:08, 8 June 2011 (UTC)

 * I don't think that the Phong reflection model is linked to computation. It may have been designed to make it possible to calculate it efficiently, but it's still just a mathematical model as the name suggests. A model that tells you how to compute something is an algorithm. In one sense Phong shading is therefore an algorithm. I don't think that the Phong reflection model is an algorithm, though. --Kri (talk) 10:26, 8 June 2011 (UTC)

 * The Phong reflection model is so basic (only vector arithmetics) that it can be translated literally to a single assignment in a Cg/HLSL/GLSL shader. Thus, it implies at least a naive algorithm. Also, this mathematical model can be considered to specify the algorithm. Thus, there are links between mathematical models and algorithms. --Martin Kraus (talk) 11:08, 8 June 2011 (UTC)

 * I see that you have removed the approximations of the Phong reflection model completely. The thing is that the section is related to both the Phong reflection model, and to Phong shading since the approximations involves interpolation of vectors. Now that there is a section about the reflection model in the article, maybe we can put "Computational approximations" as a subsection of the section "Phong reflection model"? --Kri (talk) 10:59, 8 June 2011 (UTC)

 * Well, I've removed it from Phong shading, you have removed if from Phong reflection model. I would be happy with leaving the section about (computational) approximations of the Phong reflection model in the article on the Phong reflection model. I agree that some of the approximations are specific to Phong shading; however, not all of them are. My main reason against putting it into Phong shading is that we would have to expand the section about the Phong reflection model in the article on Phong shading basically to all the core of the article about the Phong reflection model, i.e. the overlap would be very large. --Martin Kraus (talk) 11:22, 8 June 2011 (UTC)

 * I've undone your removal in this article, just to make sure that the section is not lost while we discuss where to put it. --Martin Kraus (talk) 11:30, 8 June 2011 (UTC)

 * You undid mine, but you didn't undo your own? Nice.

 * As I tried to explain, this was to avoid that we lose this section. --Martin Kraus (talk) 18:05, 8 June 2011 (UTC)

 * Okay, I thought this naive algorithm you are talking about was Phong shading. This would mean that you basically have included the whole Phong shading article here to, only without mentioning what the calculations are for (note that a mathematical model does not automatically imply calculations). That is why I feel we are taking a step against a merge again.

 * The crucial point that is not included in this article is where the normal vector comes from. For the Phong reflection model it doesn't matter where they come from. You could also just evaluate the Phong reflection model at the vertices and interpolate the resulting colors. (Which happens to be Gouraud shading.) --Martin Kraus (talk) 18:05, 8 June 2011 (UTC)

 * I think an article about a mathematical model serves a purpose just as it is; such a model can be of interest from a mathematical point of view only (which I think this can be), and for me that was actually the biggest reason for splitting the article up, to make it possible to 'cut off ' the Phong shading part from the pure mathematical part. I simply thought this part was nice as it was. A confusion between two different things can just be explained very quickly in a section in the article. If we are going to mix this article with approximations that are related to Phong shading, then that defeats the whole purpose of splitting the article up for me.

 * I agree that these approximations should not depend on Phong shading; therefore, I shortened them to include only the parts that are independent of Phong shading. As it is, this represents now alternative models that approximate the Phong reflection model (but allow for a more efficient computation). I changed the title of the section to reflect this.--Martin Kraus (talk) 18:05, 8 June 2011 (UTC)

 * If the approximations are eventually going to en up here anyway, I therefore vote for merging the two articles together again. --Kri (talk) 17:40, 8 June 2011 (UTC)

 * As they are now, they have nothing to do with Phong shading (in the sense of Phong interpolation). They are alterations of the Phong reflection model that are useful in any case (even if they are evaluated at vertices without using Phong shading). I hope this addresses your concerns. --Martin Kraus (talk) 18:05, 8 June 2011 (UTC)

 * That's the trouble with trying to slice the material too finely. Both in the original Phong method, and in Blinn's mod, and in the Lyon approximation (my stuff that's referenced), the interaction between the shading model and the interpolation method is important.  These methods don't fit cleanly into either article, but need to be in one (or both).  Dicklyon (talk) 18:34, 8 June 2011 (UTC)

 * What about another split and create an article "Lyon-Phong shading model" for these approximations? I don't want them in Phong shading, Kri doesn't want them in Phong reflection model, and Dicklyon considers it important enough to have it in Wikipedia; thus another article should please everyone. I'm in favor of it. --Martin Kraus (talk) 18:50, 8 June 2011 (UTC)

 * Reading your paper, I realized that another good reason to have a separate article for "Lyon-Phong shading model" (or similar name) is that it is also relevant for the Blinn-Phong reflection model. We cannot handle that in Phong shading unless we merge it with Blinn-Phong shading model. --Martin Kraus (talk) 19:00, 8 June 2011 (UTC)

Split of approximations to Lyon-Phong shading model
I suggest to split the section about the approximation to Lyon-Phong shading model because the Lyon-Phong shading model relies on Phong interpolation and either the Phong reflection model or the Blinn-Phong reflection model. Even if Phong interpolation and Phong reflection model is merged to one article (Phong shading), it would be impractical (and probably against some Wikipedia guidelines) to even merge it with the Blinn-Phong reflection model. But this would be necessary to cover all about the Lyon-Phong shading model. Therefore, splitting the section about the Lyon-Phong shading model appears to be the best solution. --Martin Kraus (talk) 19:08, 8 June 2011 (UTC)

 * Sorry, I might have gotten a bit grumpy before. Maybe splitting the section could be a solution. If we do split it I don't think we should call the new article Lyon-Phong shading model. The approximation methods are not not a model, since they don't aim to describe any system; they are a bunch of techniques aimed to speed up the calculation. I've taken some of the techniques from Dicklyon's paper, and the method with crossing R and V was my idea. --Kri (talk) 21:05, 8 June 2011 (UTC)

 * My method is almost certainly not notable enough to warrant its own article. Dicklyon (talk) 21:31, 8 June 2011 (UTC)

 * So, where should it go? What about Blinn-Phong shading model? That is itself already an approximation and some of Dicklyon's methods build on top of it. Thus, I would actually consider Blinn-Phong shading model a better place for these techniques then Phong reflection model and Phong shading. --Martin Kraus (talk) 21:47, 8 June 2011 (UTC)

 * No, my method works better for the Phong model than for Blinn–Phong. Leave it here on the reflection model page, since it's mostly about an efficient approximation to that.  Dicklyon (talk) 22:21, 8 June 2011 (UTC)

 * Kri: Are you aware of NOR? If it is your unpublished idea, we must delete it. I don't think there is a choice about that. --Martin Kraus (talk) 21:52, 8 June 2011 (UTC)

 * Okay, so I guess we'll just have to delete it. I don't have any source for it.

 * The section was originally written for Phong shading, before it was split up, so I honestly don't know where it fits best now; I didn't realize that Phong shading didn't have to imply the Phong reflection model until the split had already been made. My suggestions have been to either merge both the articles back again, or to place the section as a subsection under "Phong reflection model" in Phong shading. --Kri (talk) 22:15, 8 June 2011 (UTC)

 * Regarding to what Dicklyon wrote: Okay, I might after all give in on this point, if we put the approximations in a context. We still have this thing that we need to mention both the Phong reflection model and Phong shading in order to motivate the approximations fully, but now with a second look on the section, maybe it's motivated quite well already after all.

 * May I anyway suggest a name change of the section to make it clear that it's related to Phong shading (which it isn't really now)? Maybe something like "Computatinal approximations for Phong shading"? Phong shading was what the section originally was written for and I guess that when the Phong reflection model is used in graphics software (which is the motivation for the approximations), Phong shading is almost exclusively used. I also think that the paragraph mentioning the approximation $$\lambda' = ||R - V||^2 / 2 = ||D||^2 / 2.$$ should be brought back in that case. --Kri (talk) 23:27, 8 June 2011 (UTC)

 * My method can be completely independent of the interpolation, and that's how it's described there. It has the additional benefit that it doesn't require accurate normalization in the interpolation, so that can be mentioned as a side thing.  Dicklyon (talk) 01:30, 9 June 2011 (UTC)

Rewriting of the approximation section
OK, in order to avoid original research by Kri, I've removed the references to the cross product. I also brought back the discussion of the normalization. Thus, the benefit of requiring less normalization was mentioned twice, I removed the first one, and introduced a sentence to clarify that this normalization benefit is specific to Phong shading (actually, this should say Per-pixel lighting, which in practice is usually Phong shading; feel bold and change it if you think we should be more precise here). My question now is whether we should leave the discussion of missed highlights by the Lyon approximation. This isn't discussed in the reference, is it? If we don't have a reference, we should remove it. (It doesn't matter whether it is true or not.) --130.225.198.196 (talk) 08:21, 9 June 2011 (UTC)

Oops, forgot to log in. Another question: I'd like to write the specular term as $$\max(0, \hat{R}\cdot \hat{V})^\alpha$$ since this is more precise (the term should be 0 if the dot product is less than 0). This actually avoids the two cases in the first equation. Would that be OK? --Martin Kraus (talk) 08:31, 9 June 2011 (UTC)

Final question: in the approximation section, shouldn't we replace $$\lVert X \rVert^2$$ by $$X \cdot X$$ in order to make it explicit that no square root is required to evaluate this expression? --Martin Kraus (talk) 08:31, 9 June 2011 (UTC)

Another comment: I removed the reference to the Householder transformation because that transformation mirrors points at planes instead of reflecting them. And still another question: Lyon is using $$D = R - L$$ with a different R vector (the reflection of V), we are using $$D = R - V$$. Should this difference be mentioned at all? --Martin Kraus (talk) 08:59, 9 June 2011 (UTC)

 * Since no one commented on it, I was bold and implemented all these suggestions (and also replaced x by (1 - beta lambda) for clarity; remember: lambda and beta are already new variables; thus, x introduces another level of new indirect definitions which might be difficult to read for the general reader). --Martin Kraus (talk) 17:54, 10 June 2011 (UTC)

 * Looks mostly OK; I added a bit about the approximation's relative insensitivity to normalization error. The idea about interpolating the D vector seems like a good one, but I don't recall whether I or anyone has tried it.  Does it have a source?  Dicklyon (talk) 19:26, 10 June 2011 (UTC)

 * Oh, OK, I thought it was in the paper but if it isn't, then it is probably original work by Kri. I removed it. I'm not sure how relevant it is: when using a normal map, R would have to be computed per fragment; thus, the method doesn't apply. A problem of the method is that for the correct computation of D, the interpolated values of R and V have to be normalized again per fragment before the difference is computed, and that's of course not possible if D has been computed per vertex. The result is (as Kri pointed out in a long removed paragraph) that the highlight might be missed. Thinking about it, it might be better to compute D = R - (R.V)V per vertex (with normalized R and V) because this guarantees that the highlight is caught if this D is computed per vertex and V is constant and it might work well enough if V is almost constant. (Of course, when L is constant then one should compute D = R - (R.L)L .) But, OK, I've got no time to go that deep into research on optimizations of rendering specular highlights. Maybe Kri can work on it. --Martin Kraus (talk) 01:01, 11 June 2011 (UTC)

 * Well, I bet the D interpolation would work without any normalizing per pixel, as an approximation. But, as I said, I haven't tried it.  Maybe I can recreate my old code from the paper and modify it to try it.  Dicklyon (talk) 01:11, 11 June 2011 (UTC)

 * OK. I'll take the bet! :) Actually, Kri has explained it very well. Imagine (normalized) V to be constant. Let the (normalized) R vectors at the vertices of a triangle point in different directions, such that the V direction falls into a convex combination of the R vectors (the direction intersects the triangle spanned by the three R vectors). Because of the normalization the interpolated R vector will always be shorter than V and therefore the length of D will never be 0 (the interpolation plane of D doesn't contain the origin, as Kri put it). But I guess one of us has to test it, to decide the bet... --Martin Kraus (talk) 01:19, 11 June 2011 (UTC)

 * Well, I tried my idea, and it turned out that it's a very bad idea. Let's forget about it as fast as possible. ;) I tested the situation I was thinking about: orthographic view (constant V) with large triangles, such that the highlight is between vertices; shineness = 20; R and V are always normalized in the vertex shader. Results: computing D = R - V in the vertex shader misses the highlight (highlight is way too weak as Kri observed); same effect if D = R - V is computed in the fragment shader without normalization of R and V in the fragment shader. Computing D = R - V in the fragment shader from normalized interpolated R and V gives nice full highlight. Thus, I think you lost your bet. But then I realized that Kri's idea of D = R x V produces D vectors on a plane orthogonal to V, i.e. it should include the origin, i.e. guarantee to catch the highlight if V is constant. And in fact: Kri's approximation D = R x V in the vertex shader works very good (highlight has the right intensity but is a bit larger). Same result with Kri's approximation D = R x V computed from interpolated R and V in the fragment shader without normalization. With normalization in the fragment shader it produces the same (smaller) highlight as D = R - V with normalization in the fragment shader. Kri: you might be on to something (unless someone published this previously, I didn't check the literature). --Martin Kraus (talk) 02:39, 11 June 2011 (UTC)

 * Checking the shader again I realized that the view vector is actually not constant since my shader just computes the difference from vertex position to camera position in any case. However, the R vector is constant since I was using a flat plane with parallel normal vectors and a directional light source. Doing some more testing with point light sources and perspective projection revealed a couple of strange behaviors (in particular inconsistencies between Unity's interpolation in the scene view and the game view which hit the method of computing D = R - V in the scene view in the case of perspective projection and in the game view in the case of orthographic projection; actually it is weird and I don't understand what's going on). Kri's method of computing D = R x V in the vertex shader appears to be more robust in general; however, more research would be necessary, as they say when they want to have more funding. :) --Martin Kraus (talk) 10:41, 11 June 2011 (UTC)

 * As to the D = R - L, I think it doesn't matter which of the two vectors get mirrored (viewpoint or light) to compare with the other. Probably that alternative should be briefly mentioned.  I just checked my paper and was reminded that reflecting the L vector is more work when there are multiple lights.  Dicklyon (talk) 19:28, 10 June 2011 (UTC)

 * True. That optimization is applicable in any case; thus, it should be mentioned before the whole technique. Makes me wonder why the Phong model is usually formulated in the other way. --Martin Kraus (talk) 01:01, 11 June 2011 (UTC)

 * The Householder transformation does perform a reflection (see the article) and was what I used when deriving the expression for R, although I negated L before transforming it (which I maybe should have mentioned) to indicate the direction of the light instead of the direction to the light source. --Kri (talk) 16:36, 14 June 2011 (UTC)

 * Looking at the article history, I see that I did mention that L was negated before the transformation. I'm restoring the previous version of the paragraph. --Kri (talk) 17:45, 14 June 2011 (UTC)

 * On the other hand, the link to Specular reflection that is currently in the article works too for explaining why the expression looks as it does. --Kri (talk) 18:36, 14 June 2011 (UTC)

REally, summed ambient - are your sure !
". A single term i a {\displaystyle i_{\text{a}}} i_{\text{a}} controls the ambient lighting; it is sometimes computed as a sum of contributions from all light sources. "

It would never be correct to sum the 'ambient' value of a light, even assuming that it has one. As you would eventually saturate to white a scene with ( say ) 20 spotlights all looking at different parts of the scene / object. It is an error to sum the ambients and it is not in the given equation. — Preceding unsigned comment added by 82.8.228.52 (talk) 18:41, 10 November 2016 (UTC)
 * You're correct. The ambient term is an approximation of the effect of lighting that isn't directly attributed to the primary light sources, but to diffuse light bouncing from walls, the floor, clouds and so on.

Opening paragraph is misleading
The way I read the opening paragraph, it seemed to mean that people had actually measured the behaviour of various physical materials and this resulted in this shading model, but this turns out not to be the case. Rather, it's a simple model that kind of looks decent on screen.

"No Original Research" policy must be observed
I am currently writing a 3D renderer using Phong shading. I have just wasted two days of work time as a direct result of this page violating Wikipedia's "No Original Research" policy. The approximation section, at the time of writing, contains the following:

Furthermore, the value $$\lambda$$ can be approximated as $$\lambda = (\hat{R}_m - \hat{V})\cdot(\hat{R}_m - \hat{V}) / 2$$, or as $$\lambda = (\hat{R}_m \times \hat{V})\cdot(\hat{R}_m \times \hat{V}) / 2.$$ The latter is much less sensitive to normalization errors in $$\hat{R}_m$$ and $$\hat{V}$$ than Phong's dot-product-based $$\lambda = 1 - \hat{R}_m \cdot \hat{V}$$ is, and practically doesn't require $$\hat{R}_m$$ and $$\hat{V}$$ to be normalized except for very low-resolved triangle meshes.

The former of these two approximations is the one cited in Lyon's (excellent) paper which is referenced for this section.

The latter claim, regarding $$\lambda = (\hat{R}_m \times \hat{V})\cdot(\hat{R}_m \times \hat{V}) / 2.$$ is not mentioned as an approximation in Lyon's 1993 paper anywhere. It appears to be original research added by editor Kri (25-Aug-2015) over 4 years after the discussion on this talk page resolved to remove his original research from the page.

This approximation and its associated claims must be sourced with an appropriate reference which contains the derivation of the approximation and derivation of the claims about requiring no vector normalization.

If cited sources are not forthcoming then I will remove this sentence from the article.

--Ipeakiwi (talk) 23:32, 9 April 2022 (UTC)

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