Mirror
/
cpython
mirror of https://github.com/python/cpython
4
1
Fork 0
Code Issues Releases Wiki Activity

Issue #28256: Cleanup _math.c 

Only define fallback implementations when needed. It avoids producing deadcode
when the system provides required math functions.
This commit is contained in:
Victor Stinner 2016-10-18 16:29:27 +02:00
parent 22e36afc17
commit bf9655854b
2 changed files with 41 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
Modules/_math.c
View File

@ -19,13 +19,19 @@
* ====================================================
*/
#if !defined(HAVE_ACOSH) || !defined(HAVE_ASINH)
static const double ln2 = 6.93147180559945286227E-01;
static const double two_pow_m28 = 3.7252902984619141E-09; /* 2**-28 */
static const double two_pow_p28 = 268435456.0; /* 2**28 */
#ifndef Py_NAN
#endif
#if !defined(HAVE_ASINH) || !defined(HAVE_ATANH)
static const double two_pow_m28 = 3.7252902984619141E-09; /* 2**-28 */
#endif
#if !defined(HAVE_ATANH) && !defined(Py_NAN)
static const double zero = 0.0;
#endif
#ifndef HAVE_ACOSH
/* acosh(x)
* Method :
* Based on
@ -74,8 +80,10 @@ _Py_acosh(double x)
return m_log1p(t + sqrt(2.0 * t + t * t));
}
}
#endif /* HAVE_ACOSH */
#ifndef HAVE_ASINH
/* asinh(x)
* Method :
* Based on
@ -112,7 +120,10 @@ _Py_asinh(double x)
return copysign(w, x);
}
#endif /* HAVE_ASINH */
#ifndef HAVE_ATANH
/* atanh(x)
* Method :
* 1.Reduced x to positive by atanh(-x) = -atanh(x)
@ -160,7 +171,10 @@ _Py_atanh(double x)
}
return copysign(t, x);
}
#endif /* HAVE_ATANH */
#ifndef HAVE_EXPM1
/* Mathematically, expm1(x) = exp(x) - 1. The expm1 function is designed
to avoid the significant loss of precision that arises from direct
evaluation of the expression exp(x) - 1, for x near 0. */
@ -186,16 +200,17 @@ _Py_expm1(double x)
else
return exp(x) - 1.0;
}
#endif /* HAVE_EXPM1 */
/* log1p(x) = log(1+x). The log1p function is designed to avoid the
significant loss of precision that arises from direct evaluation when x is
small. */
#ifdef HAVE_LOG1P
double
_Py_log1p(double x)
{
#ifdef HAVE_LOG1P
/* Some platforms supply a log1p function but don't respect the sign of
zero: log1p(-0.0) gives 0.0 instead of the correct result of -0.0.
@ -208,13 +223,7 @@ _Py_log1p(double x)
else {
return log1p(x);
}
}
#else
double
_Py_log1p(double x)
{
/* For x small, we use the following approach. Let y be the nearest float
to 1+x, then
@ -252,6 +261,6 @@ _Py_log1p(double x)
/* NaNs and infinities should end up here */
return log(1.+x);
}
#endif /* ifdef HAVE_LOG1P */
}
#endif /* ifdef HAVE_LOG1P */

12
Modules/_math.h
View File

@ -1,14 +1,9 @@
double _Py_acosh(double x);
double _Py_asinh(double x);
double _Py_atanh(double x);
double _Py_expm1(double x);
double _Py_log1p(double x);
#ifdef HAVE_ACOSH
# define m_acosh acosh
#else
/* if the system doesn't have acosh, use the substitute
function defined in Modules/_math.c. */
double _Py_acosh(double x);
# define m_acosh _Py_acosh
#endif
@ -17,6 +12,7 @@ double _Py_log1p(double x);
#else
/* if the system doesn't have asinh, use the substitute
function defined in Modules/_math.c. */
double _Py_asinh(double x);
# define m_asinh _Py_asinh
#endif
@ -25,6 +21,7 @@ double _Py_log1p(double x);
#else
/* if the system doesn't have atanh, use the substitute
function defined in Modules/_math.c. */
double _Py_atanh(double x);
#define m_atanh _Py_atanh
#endif
@ -33,9 +30,12 @@ double _Py_log1p(double x);
#else
/* if the system doesn't have expm1, use the substitute
function defined in Modules/_math.c. */
double _Py_expm1(double x);
#define m_expm1 _Py_expm1
#endif
double _Py_log1p(double x);
/* Use the substitute from _math.c on all platforms:
it includes workarounds for buggy handling of zeros. */
#define m_log1p _Py_log1p