View source for Ulp

{{also|ULP}}
==English==
{{was wotd|2019|November|17}}

===Pronunciation===
* {{IPA|en|/ʌlp/|a=RP,GA}}
** {{audio|en|LL-Q1860 (eng)-Vealhurl-ulp.wav|a=Southern England}}

===Etymology 1===
{{glossary|Imitative}}, or possibly a variant of {{m|en|gulp}}.

====Interjection====
{{en-interj}}

# {{non-gloss|The [[sound#Noun|sound]] of a [[person]] [[gulp#Verb|gulping]] in [[fear#Noun|fear]].}}
#: {{synonyms|en|gulp}}
#* {{quote-book|en|author=w:Charlie Connelly|title=And Did Those Feet: Walking through 2000 Years of British and Irish History|url=https://books.google.com/books?id=KFyy1j1hZygC&pg=PT40|location=London|publisher=w:Little, Brown and Company|year=2009|isbn=978-1-4087-0084-6|passage=I sent her a text asking as nonchalantly as possible whether cows ever go for you. [...] The answer I got was, 'Occasionally they do, and they can be bloody scary.' '''Ulp'''.}}
#* {{quote-journal|en|author=Joel Rubinoff|title=Train wreck keeps rollin’ along|url=https://www.thestar.com/entertainment/2009/02/10/train_wreck_keeps_rollin_along.html|archiveurl=https://web.archive.org/web/20160312154305/https://www.thestar.com/entertainment/2009/02/10/train_wreck_keeps_rollin_along.html|archivedate=12 March 2016|newspaper=w:Toronto Star|location=Toronto, Ont.|publisher=Toronto Star Newspapers|date=10 February 2009|issn=0319-0781|oclc=909907143|passage=And where would the Grammys be without Motown maverick {{w|Stevie Wonder}}, continuing his slide into musical irrelevance with a mind-boggling collaboration with, '''ulp''', teen idols the {{w|Jonas Brothers}}, who massacred their own "[[w:Burnin' Up (Jonas Brothers song)|Burnin' Up]]" and Stevie's "[[w:Superstition (song)|Superstition]]" with boyish aplomb.}}
#* {{quote-book|en|author=[[w:Jennifer Stevenson (author)|Jennifer Stevenson]]|title=It’s Raining Angels and Demons|series=Slacker Demons|seriesvolume=book 2|location=Lancaster, Oh.|publisher=Calliope|year=2012|isbn=978-1-61937-305-1|passage=Little—'''ulp'''—little red horns curving out of his brow. My mouth was totally dry.}}

=====Translations=====
{{trans-see|''sound of a person gulping in fear''|gulp}}

===Etymology 2===
{{abbrev|en|[[unit]] in the [[last]] [[place]],[[unit]] of [[least]] [[precision]]}}, coined in 1960 by Canadian mathematician and computer scientist {{w|William Kahan}} (born 1933).<ref>{{cite-book|author=Jean-Michel Muller [''et al.'']|chapter=Definitions and Basic Notions|title=Handbook of Floating-Point Arithmetic|location=Boston, Mass.; Basel|publisher={{w|Birkhäuser}}|year=2010|section=section 2.6.1 (The Ulp Function)|page=32|pageurl=https://books.google.com/books?id=baFvrIOPvncC&pg=PA32|doi=10.1007/978-0-8176-4705-6|isbn=978-0-8176-4704-9}}.</ref>

====Noun====
{{en-noun}}

# {{lb|en|computer science|mathematics}} The [[value#Noun|value]] that the [[least]] [[significant]] [[digit]] of a [[floating-point number]] [[represent]]s, [[use#Verb|used]] as a [[measure#Noun|measure]] of [[accuracy]] in [[numeric#Adjective|numeric]] [[calculation]]s. {{defdate|From 1960}}
#* {{quote-book|en|author=w:Webb Miller; Celia Wrathall|chapter=Software for Roundoff Analysis|title=Software for Roundoff Analysis of Matrix Algorithms|location=New York, N.Y.; London|publisher=w:Academic Press|year=1980|section=section 4.2 (Rounding and Perturbations of the Computational Problem)|page=86|pageurl=https://books.google.com/books?id=8rfiBQAAQBAJ&pg=PA86|isbn=978-0-12-497250-6|passage=The basic concept of two vectors "agreeing to ''k'' '''ulps'''" (units in the last place) of each entry or of the largest entry allows us to express relationships among computed values and solutions at perturbed data.}}
#* {{quote-book|en|author=[[w:Donald Knuth|Donald E[rvin] Knuth]]|chapter=Arithmetic|title=w:The Art of Computer Programming|series=Addison-Wesley Series in Computer Science and Information Processing|edition=2nd|location=Reading, Mass.|publisher=w:Addison-Wesley|year=1981|volume=2 (Seminumerical Algorithms)|page=217|isbn=978-0-201-03822-4|edition2=3rd|location2=Reading, Mass.|publisher2=Addison-Wesley|year2=1997|section2=section 4.2.2 (Accuracy of Floating Point Arithmetic)|sectionurl2=https://books.google.com/books?id=Zu-HAwAAQBAJ&pg=PT390|isbn2=978-0-201-89684-8|passage=Floating point operations are correct to within half an '''ulp''', and the calculation of ''uvw'' by two floating point multiplications will be correct within about one '''ulp''' (ignoring second-order terms).}}
#* {{quote-book|en|chapter=Numerical Mathematics|mainauthor=Victor Adamchik; et al.|editor=Emily Martin|title=Mathematica 3.0 Standard Add-on Packages|location=Champaign, Ill.|publisher=[[w:Wolfram Research|Wolfram Media]]; Cambridge, Cambridgeshire: {{w|Cambridge University Press}}|year=1996|page=369|pageurl=https://books.google.com/books?id=VnH0UzTycTcC&pg=PA369|isbn=978-0-9650532-3-5|passage=The difference between two consecutive machine numbers is called an '''ulp''' (''u''nit in the ''l''ast ''p''lace, ''i.e.'', one digit in the least significant place). The size of an '''ulp''' varies depending on where you are in the set of machine numbers. [...] Ideally no function should ever return a result with error exceeding half of an '''ulp''' since the distance from the true result to the nearest machine number is always less than half of an '''ulp''', the worst case being when it is exactly halfway between two machine numbers.}}
#* {{quote-book|en|author=Jean-Michel Muller; et al.|chapter=Definitions and Basic Notions|title=Handbook of Floating-Point Arithmetic|location=Boston, Mass.; Basel|publisher=w:Birkhäuser|year=2010|section=section 2.6.1 (The Ulp Function)|page=34|pageurl=https://books.google.com/books?id=baFvrIOPvncC&pg=PA34|doi=10.1007/978-0-8176-4705-6|isbn=978-0-8176-4704-9|passage=If, instead of considering '''ulps''' of the "exact" value <math>x</math>, we consider '''ulps''' of the floating-point value <math>X</math>, we have a property that is very similar to Property 2, with the interesting difference that it now holds for any value of the radix.}}

=====Translations=====
{{trans-top|value that the least significant digit of a floating-point number represents}}
* Italian: {{t|it|ulp|f}}
{{trans-bottom}}

===References===
<references />

===Further reading===
* {{pedia|unit in the last place}}

===Anagrams===
* {{anagrams|en|a=lpu|PLU|UPL|pul}}

==Italian==

===Noun===
{{it-noun|f|#}}

# {{lb|it|computer science|mathematics}} {{l|en|ulp|t=[[unit]] in the [[last#Adjective|last]] [[place#Noun|place]] (unità in ultima posizione) or unit of [[least]] [[precision]] (unità di minore precisione)}}