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:::I just looked at some implementation I did of the whole business I did ages ago and I did actually use three bits! Just me forgetting what I'd done, sorry. yes the subtraction does actually require them all. [[User:Dmcq|Dmcq]] ([[User talk:Dmcq|talk]]) 11:33, 9 March 2012 (UTC)
== edit : computation in page is correct after all ==
Sorry for the confusion : I used t_(i+1) instead of t_i. for that reason I missed a factor 2 : 2^(i+1) = 2 * 2^i. <small><span class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:KeesLem|KeesLem]] ([[User talk:KeesLem|talk]] • [[Special:Contributions/KeesLem|contribs]]) 14:36, 21 February 2013 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->
== Justification for division by zero definition ==
I [http://en.wikipedia.org/w/index.php?title=Division_by_zero&diff=511812597&oldid=510158610 recently added] to [[division by zero]] this statement with an appropriate source:
:"The justification for this definition is to preserve the sign of the result in case of [[arithmetic underflow]]. For example, in the double-precision computation 1/(''x''/2), where ''x'' = ±2<sup>−149</sup>, the computation ''x''/2 underflows and produces ±0 with sign matching ''x'', and the result will be ±∞ with sign matching ''x''. The sign will match that of the exact result ±2<sup>150</sup>, but the magnitude of the exact result is too large to represent, so infinity is used to indicate overflow."
Provided this is valid, I wonder if it could also be added in some relevant ___location in the body of floating point related articles. In general I'd like to see more information on design rationales. Thanks! [[User:Dcoetzee|Dcoetzee]] 07:42, 11 September 2012 (UTC)
== Signed zero section, branch cuts ==
The section on signed zero (under Internal representation >> Special values >> Signed zero) says the following:
"The difference between +0 and −0 is mostly noticeable for complex operations at so-called [[Branch cut|branch cuts]]."
In a strictly mathematical sense, +0/-0 ''can'' be interpreted as describing the limiting behaviors of a function, but that's not actually what's happening here. Moreover, branch cuts are not the only situation where these exceptional limiting behaviors appear, one can have branch cuts without exceptional limiting behaviors of this sort, and none of the examples given in the section are actually branch cuts. As far as I can tell, there is absolutely no significance to the relationship between branch cuts in complex analysis and signed zero in floating point numerical representations, but I wanted to make sure there wasn't a good reason for this being here. Thoughts? [[Special:Contributions/71.227.119.236|71.227.119.236]] ([[User talk:71.227.119.236|talk]]) 15:25, 29 September 2012 (UTC)
:Result of a quick Google search:
:"A system with signed zero can distinguish between asin(5+0i) and asin(5-0i) and pick the appropriate branch cut continuous with quadrant I or quadrant IV, respectively. A system without signed zero cannot distinguish and, according to the choses the branch cut such that it is continuous with quadrant IV (consistent with the rule of CCC). So, for asin(5+0i) it will return the same value as a system with signed zero would for asin(5-0i)." -Richard B. Kreckel ( [ http://www.ginac.de/~kreckel/ ] [ http://lists.gnu.org/archive/html/bug-gsl/2011-12/msg00004.html ] ).
:I think that when he wrote "according to the" he meant "accordingly" (probably not a native English speaker). --[[User:Guy Macon|Guy Macon]] ([[User talk:Guy Macon|talk]]) 23:34, 29 September 2012 (UTC)
::Somewhat straying from the subject but still quite interesting; the "Signed Zero" section of "What Every Computer Scientist Should Know About Floating-Point Arithmetic" ( [ http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html ] ) --[[User:Guy Macon|Guy Macon]] ([[User talk:Guy Macon|talk]]) 23:41, 29 September 2012 (UTC)
== imho, the computation for Pi as shown actually computes only Pi/2 ==
The algorithm as shown to compute an approximation of Pi actually computes imo in this form only Pi/2, even while the output shown contains
an approximation for Pi. I think either the values should be halved or the formula should be changed into : 12 * 2^i * t_i
[[User:KeesLem|KeesLem]] ([[User talk:KeesLem|talk]]) 15:16, 21 February 2013 (UTC) <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/130.161.210.156|130.161.210.156]] ([[User talk:130.161.210.156|talk]]) </span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
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