Fixed the precision of expm1(float x) when x is small.
#517
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…re provided, one with 12.0 bits of precision, and another with 16.0 bits of precision. Tested all inputs on x86_64
adriweb
reviewed
Nov 8, 2024
| @@ -1,8 +1,24 @@ | |||
| #include <math.h> | |||
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| float expm1f(float x) | |||
| float expm1f(const float x) | |||
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Why? That's not needed or in the standard.
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Adding const to parameters passed by value doesn't change the ABI. It can prevent accidentally modifying the input, but it was a more of a micro optimization I added. It probably doesn't change the compiler output
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The accuracy of expm1f(float x) has been fixed. It will
return xwhenxis small for 12.0bits of precision, or it canreturn x + 0.5f * (x * x)whenxis small for 16.0bits of precision. It falls-back to the naivereturn expf(x) - 1.0fwhenxis large.