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| author | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2017-04-03 09:16:27 +0000 |
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| committer | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2017-04-03 09:16:27 +0000 |
| commit | 1543c40a4bf927230a0f93236f71688647a2ff32 (patch) | |
| tree | b87a4d59ec2a8ad4b053aeee9da6b4b319c36f2d /src/atanh.c | |
| parent | 5e952138d666c5f9ecef9d29ebd081bb6448204d (diff) | |
| download | mpfr-1543c40a4bf927230a0f93236f71688647a2ff32.tar.gz | |
[TODO,src/atanh.c] Suggest a faster formula for atanh(x) on small x.
git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@11398 280ebfd0-de03-0410-8827-d642c229c3f4
Diffstat (limited to 'src/atanh.c')
| -rw-r--r-- | src/atanh.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/atanh.c b/src/atanh.c index 298cb61e3..7b10c5abc 100644 --- a/src/atanh.c +++ b/src/atanh.c @@ -25,6 +25,10 @@ http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., /* The computation of atanh is done by: atanh = ln((1+x)/(1-x)) / 2 + except when x is very small, in which case atanh = x + tiny error. + TODO: When x is small (but x + tiny error cannot be used), the above + formula is slow due to the large error as (1+x)/(1-x) is close to 1; + one should use: log1p(2x/(1-x)). */ int |