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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 |