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[PATCH libstdc++/66689] comp_ellint_3 and ellint_3 return garbage values

From: Ed Smith-Rowland <3dw4rd at verizon dot net>
To: "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>, Jonathan Wakely <jwakely dot gcc at gmail dot com>, redi at gcc dot gnu dot org
Date: Fri, 17 Nov 2017 15:05:55 -0500
Subject: [PATCH libstdc++/66689] comp_ellint_3 and ellint_3 return garbage values
Authentication-results: sourceware.org; auth=none

This is an embarrassment actually, after the excellent analysis in thePR trail.

We've (I've) been using the wrong sign convention for the nu parameterin comp_ellint_3 and in ellint_3 in tr1 and now std for years. In mydefence the World seems about evenly split on this with GSL,Abramowitz&Stegun (and DLMF) and Carlson (that's what actually got mehere) on the +nu side, and tr1/std, boost on the other -nu side.


We need to get this into 8.

I'm not sure about backporting to 7. I don't think we should changethis breaking in the middle of a release series.

I'll write a Mea Culpa warning about changing ellint_3, comp_ellint_3 inthe release notes and in the libstdc++ pages and the tr29124 conformancepage later.


This builds and passes on x86-64-linux.

OK for 8?

Ed

Attachment: pr66689.CL
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Attachment: pr66689.patch.bz2
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