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== Title ==
I think this article should be moved, since the title is not conform to IEEE 754r, which refers the format as '''quad''' or '''quadruple precision''', but never '''quad precision'''. Also '''quad''' is not really an adjective like '''single''' and '''double'''. See e.g. the draft on [http://754r.ucbtest.org/]. — [[User:Ylai|Ylai]] 08:53, 9 January 2006 (UTC)
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These statements contradict each other.
:It appears this has been cleaned up. -[[User:JakeVortex|Jake]] ([[User talk:JakeVortex|talk]]) 04:27, 20 September 2014 (UTC)
== Max quad begins with (hex) 7fef or 7ffe? ==
I think it should probably be "7ffe" in the first block of four hex digits unless anyone can say why not.
:Yes, <code>7ffe</code> -[[User:JakeVortex|Jake]] ([[User talk:JakeVortex|talk]]) 04:27, 20 September 2014 (UTC)
== Possible Error in the Example for 1/3 ==
Line 79 ⟶ 81:
The IBM z Series supports quad precision. See: [http://www.research.ibm.com/journal/rd/483/gerwig.pdf this paper], Figure 1. [[User:Mfc|mfc]] ([[User talk:Mfc|talk]]) 11:59, 10 March 2009 (UTC)
:The [[VAX]] had support for 128-bit floats (called h_float) since the 1970s, but it's not IEEE 754-compliant. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/69.54.60.34|69.54.60.34]] ([[User talk:69.54.60.34|talk]]) 14:04, 15 September 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->▼
IBM hex (base 16) floating point has supported extended (128 bit) precision starting with the 360/85, and all models of S/370 and successors, except that DXR (extended precision divide) was done in software emulation until part way through the ESA/390 years. Newer processors implement binary (IEEE) and decimal (IEEE) floating point, including extended (128 bit) precision. [[User:Gah4|Gah4]] ([[User talk:Gah4|talk]]) 00:01, 25 October 2011 (UTC)
▲
[[VAX]] still supports H-Float, but it is implemented through software emulation on most models, or optional microcode. The VAX 11/730, implemented in microcode through the AMD2900 series bit-slice logic, normally came with H-Float. [[User:Gah4|Gah4]] ([[User talk:Gah4|talk]]) 00:01, 25 October 2011 (UTC)
Some (all?) PowerPC CPUs supports quadprecision nativly. Also few compilers like Intel Fortran compiler (but few others also) supports quad-precision (not sure if strictly IEEE754, but they do) on x86 and amd64 systems using only double precision numbers with additions of some refinments or software functions. There is also few (about 3), lightwaight and fast libraries for quad and octal precision using 2xdouble (or 4xfloat for old architecture) or 4xdouble, but they do not have only about 90% precision of real quad or octal floating point numbers. One of such libraries is QD and DDFUN90 library. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/91.213.255.7|91.213.255.7]] ([[User talk:91.213.255.7|talk]]) 03:16, 11 June 2011 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->▼
: About PowerPC - we can add this information, but can you provide and link to the articles (e.g. magazine articles, IBM's articles, any conference paper, but not a forum or non-IBM wokrer blog) which will explicitly say about hardware support of quad (128-bit) floating point in hardware? `[[User:A5b|a5b]] ([[User talk:A5b|talk]]) 14:22, 3 August 2011 (UTC)
::I think the anon is confusing compiler support for hardware support. Several PowerPC compilers support a quadruple precision type, but they do so by compiling to a software implementation -- PowerPC hardware only has instructions for single and double precision as far as I know. [[User:Stevenj|— Steven G. Johnson]] ([[User talk:Stevenj|talk]]) 22:36, 4 August 2011 (UTC)
:::On PowerPC (Mac OS X and GNU/Linux) the long double C type corresponds to the double-double arithmetic (implemented in software). [[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 00:43, 16 February 2012 (UTC)
== Link to Multiprecision Computing Toolbox for MATLAB ==
A link to Multiprecision Computing Toolbox for MATLAB was added, which is fine since according to http://www.advanpix.com/2013/01/20/fast-quadruple-precision-computations/ this toolbox has specific, optimized support for IEEE quadruple precision (not just generic arbitrary precision). However this is a bit hidden. I think that some reference to this page from the changelog should be given, but I wonder what form it should take (this cannot be a real reference, since the external links appear after the references).
[[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 17:39, 12 April 2013 (UTC)
:Links to specific commercial systems such as this one are not appropriate per [[WP:ELNO]], I removed it again. - [[User:MrOllie|MrOllie]] ([[User talk:MrOllie|talk]]) 10:04, 17 September 2013 (UTC)
::Any commercial software or product can be described as "specific commercial system". I think there is some major misunderstanding since Wikipedia has a lot references to "specific commercial systems" like Microsoft Windows, MATLAB, Intel CPUs, etc. This page alone contains links to Microsoft Visual C++, Intel C++/Fortran compiler and even SPARC processor - all of which are very "specific commercial systems". The Multiprecision Computing Toolbox for MATLAB is no different from these tools. Toolbox adds quadruple-precision floating-point support to MATLAB system. It is used by hundreds of researchers around the globe, cited in dozens of scientific papers and books (citations appeared just in last several months: http://www.advanpix.com/2015/04/02/citations-digest-v-4/). Why do you think it is not good enough for Wikipedia?
::[[WP:ELNO]] is designed to prevent the scam, spam and links to malicious/harmful resources. It has no any signs of crusade against "specific commercial systems". Obviously removal of all references to "specific commercial systems" would make the article (and Wikipedia in general) shallow and non-informative.
::Could you please explain in detail your reasoning and provide exact item number from [[WP:ELNO]] which toolbox falls under? [[User:Kletka|Kletka]] ([[User talk:Kletka|talk]]) 02:55, 20 June 2015 (UTC)
:::Now I think that there should be a third subsection "Libraries and toolboxes" for [[Quadruple-precision floating-point format#Implementations|Implementations]], and these external links would mainly be references (unless there already is a Wikipedia article for them). – [[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 11:05, 20 June 2015 (UTC)
::::I think this would work nicely. Actually, as a draft, I have added such sub-section with two references. Please revise/remove it or let's discuss further. I have added link to toolbox if no other complains exist. [[User:Kletka|Kletka]] ([[User talk:Kletka|talk]]) 02:35, 22 June 2015 (UTC)
:::::They were not references, but external links. I've replaced them by references, with more accurate URL's about the features in question. – [[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 22:12, 22 June 2015 (UTC)
::::::Yes, definitely, this is much better. Will follow the style in future. [[Special:Contributions/223.218.164.210|223.218.164.210]] ([[User talk:223.218.164.210|talk]]) 02:24, 23 June 2015 (UTC)
== External links modified ==
Hello fellow Wikipedians,
I have just modified {{plural:2|one external link|2 external links}} on [[Quadruple-precision floating-point format]]. Please take a moment to review [https://en.wikipedia.org/w/index.php?diff=prev&oldid=716259763 my edit]. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit [[User:Cyberpower678/FaQs#InternetArchiveBot|this simple FaQ]] for additional information. I made the following changes:
*Corrected formatting/usage for http://h21007.www2.hp.com/portal/download/files/unprot/intel/product_brief_Fortran_Linux.pdf
*Added archive http://web.archive.org/web/20121009191824/http://developer.apple.com/legacy/mac/library/documentation/Performance/Conceptual/Mac_OSX_Numerics/Mac_OSX_Numerics.pdf to http://developer.apple.com/legacy/mac/library/documentation/Performance/Conceptual/Mac_OSX_Numerics/Mac_OSX_Numerics.pdf
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Cheers.—[[User:Cyberbot II|<sup style="color:green;font-family:Courier">cyberbot II</sup>]]<small><sub style="margin-left:-14.9ex;color:green;font-family:Comic Sans MS">[[User talk:Cyberbot II|<span style="color:green">Talk to my owner</span>]]:Online</sub></small> 19:07, 20 April 2016 (UTC)
== Add minimum to examples? ==
<pre>
0001 0000 0000 0000 0000 0000 0000 0000 ≈ -1.189731495357231765085759326628008 × 10<sup>-4932</sup>
(min quadruple precision)
</pre>
This probably needs to be added for those wishing to know what the minimum is in hexadecimal. However, I am not sure if it is truely `-1.189...7 + 0.0...1 x 10<sup>-4932</sup>`. I didn't calculate it.
Much love, [[User:PauSix|PauSix]] ([[User talk:PauSix|talk]]) 03:27, 20 October 2018 (UTC)
:Last November I added more examples to all the various floating-point formats, so that (hopefully) they all contain the same set of examples. The minimum value mentioned above was added as "smallest positive normal number". [[User:Pjacklam|Peter J. Acklam]] ([[User talk:Pjacklam|talk]]) 07:44, 7 August 2019 (UTC)
== Conversion to binary and back ==
The sentence "If a decimal string with at most 33 significant digits is converted to IEEE 754 quadruple-precision representation, and then converted back to a decimal string with the same number of digits, the final result should match the original string" is only true if the quadruple precision representation is a normal number. Subnormals have less precision and proportionately fewer decimal digits are allowed. The wikipedia article for double precision floating-point format has the same issue. [[Special:Contributions/2601:18C:4200:60F0:845C:148F:C31C:6449|2601:18C:4200:60F0:845C:148F:C31C:6449]] ([[User talk:2601:18C:4200:60F0:845C:148F:C31C:6449|talk]]) 13:48, 15 August 2022 (UTC)
:Thanks (and this won't work either in case of overflow, though this is a bit more obvious). I've just done the correction in [[Quadruple-precision floating-point format]], [[Double-precision floating-point format]] and [[Single-precision floating-point format]]. — [[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 17:43, 17 August 2022 (UTC)
== Broken Link ==
Reference 1, which is:
David H. Bailey; Jonathan M. Borwein (July 6, 2009). "High-Precision Computation and Mathematical Physics" (PDF).
no longer works for me. [[Special:Contributions/64.16.131.2|64.16.131.2]] ([[User talk:64.16.131.2|talk]]) 21:45, 22 February 2023 (UTC)
:Thanks for the information. I've just updated the URL. — [[User:Vincent Lefèvre|Vincent Lefèvre]] ([[User talk:Vincent Lefèvre|talk]]) 21:58, 22 February 2023 (UTC)
== request about discussion / seek consensus for the info about different understanding of the encodings ==
I added an info about 'integral understanding of the significand', fully backed by IEEE standard paper and with citation, the user Vincent Lefèvre like to delete it repeatedly. IMHO it's against WP policy about different opinions, he should seek consenus here!
== request to block user Vincent Lefèvre from 'silly reverts' ==
▲Some (all?) PowerPC CPUs supports quadprecision nativly. Also few compilers like Intel Fortran compiler (but few others also) supports quad-precision (not sure if strictly IEEE754, but they do). There is also few (about 3), lightwaight and fast libraries for quad and octal precision using 2xdouble (or 4xfloat for old architecture) or 4xdouble, but they do not have only about 90% precision of real quad or octal floating point numbers. One of such libraries is QD and DDFUN90 library. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/91.213.255.7|91.213.255.7]] ([[User talk:91.213.255.7|talk]]) 03:16, 11 June 2011 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
I am not the only user who is annoyed by stupid aggressive deletions by the user Vincent Lefèvre, see his talk page. Is there a way to stop this blockwart behavior?
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