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| author | Damien George <damien.p.george@gmail.com> | 2018-09-04 16:59:08 +1000 |
|---|---|---|
| committer | Damien George <damien.p.george@gmail.com> | 2018-09-04 17:00:30 +1000 |
| commit | afc7ddca311e9c5d785537bbadb86cabf8634bea (patch) | |
| tree | 2e9ea4c8cb67f4d13f92403b9bb35487ff78bed7 /lib | |
| parent | 0b239d458cb87176089f046756e5deebe24814eb (diff) | |
| download | micropython-afc7ddca311e9c5d785537bbadb86cabf8634bea.tar.gz micropython-afc7ddca311e9c5d785537bbadb86cabf8634bea.zip | |
lib/libm/math: Make tanhf more efficient and handle large numbers.
Prior to this patch tanhf(large number) would return nan due to inf/inf.
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libm/math.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/lib/libm/math.c b/lib/libm/math.c index 6b65202cf0..d2c3949957 100644 --- a/lib/libm/math.c +++ b/lib/libm/math.c @@ -52,10 +52,14 @@ static const float _M_LN10 = 2.30258509299404; // 0x40135d8e float log10f(float x) { return logf(x) / (float)_M_LN10; } float tanhf(float x) { - if (isinf(x)) { - return copysignf(1, x); + int sign = 0; + if (x < 0) { + sign = 1; + x = -x; } - return sinhf(x) / coshf(x); + x = expm1f(-2 * x); + x = x / (x + 2); + return sign ? x : -x; } /*****************************************************************************/ |