patchGNU Octave - Patches: patch #8172, Improve complex mapper functions...


patch #8172: Improve complex mapper functions (see Numerical, item 2 on Projects page)

Submitted by:  Craig Hudson <craighudson>
Submitted on:  Fri 30 Aug 2013 01:04:39 PM UTC  
Category: NonePriority: 5 - Normal
Status: NonePrivacy: Public
Assigned to: NoneOpen/Closed: Open

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Fri 30 Aug 2013 01:04:39 PM UTC, original submission:

This includes code for making use of signed zero, as described in Branch Cuts for Complex Elementary Functions, or Much Ado About Nothing's Sign Bit by W. Kahan. Note that casts of complex numbers with imaginary part equal to zero to real numbers previously occurred with both positive and negative zero, but now only occurs with positive zero. There is a case for not doing this narrowing conversion with either sign of zero, as (eg) dividing a real number by a complex number with imaginary part equal to positive zero gives the wrong sign of the zero imaginary part to the result. eg 1/(1 + 0i) should be 1 - 0i, but is calculated as 1 due to the denominator being cast to a real value.

Craig Hudson <craighudson>


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Attach File(s):

Attached Files
file #28959:  change.diff added by craighudson (46KiB - text/x-patch)


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    Date Changed By Updated Field Previous Value => Replaced By
    Fri 30 Aug 2013 01:04:39 PM UTCcraighudsonAttached File-=>Added change.diff, #28959

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