[Octave-patch-tracker] [patch #8172] Improve complex mapper functions (see Numerical, item 2 on Projects page)

[Craig Hudson]

URL:
  <http://savannah.gnu.org/patch/?8172>

                 Summary: Improve complex mapper functions (see Numerical,
item 2 on Projects page)
                 Project: GNU Octave
            Submitted by: craighudson
            Submitted on: Fri 30 Aug 2013 01:04:39 PM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

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 + 0*i) should be 1 - 0*i,
but is calculated as 1 due to the denominator being cast to a real value.



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File Attachments:


-------------------------------------------------------
Date: Fri 30 Aug 2013 01:04:39 PM GMT  Name: change.diff  Size: 46kB   By:
craighudson

<http://savannah.gnu.org/patch/download.php?file_id=28959>

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