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2 * mingwex/Makefile.in (MATH_DISTFILES): Remove pow.c,

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(MATH_OBJS): Remove pow,o.
	* include/math.h (pow): Declare with _CRTIMP.
	Add comment on how to avoid excess precision problems.
This commit is contained in:
Danny Smith
2004-07-02 10:01:51 +00:00
parent 2cb47d686e
commit 64b9893f0d
3 changed files with 48 additions and 7 deletions
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44
winsup/mingw/include/math.h
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@ -129,7 +129,6 @@ struct _exception
double retval;
};
_CRTIMP double __cdecl sin (double);
_CRTIMP double __cdecl cos (double);
_CRTIMP double __cdecl tan (double);
@ -143,10 +142,7 @@ _CRTIMP double __cdecl atan2 (double, double);
_CRTIMP double __cdecl exp (double);
_CRTIMP double __cdecl log (double);
_CRTIMP double __cdecl log10 (double);
#ifdef __NO_ISOCEXT
_CRTIMP
#endif
double __cdecl pow (double, double);
_CRTIMP double __cdecl pow (double, double);
_CRTIMP double __cdecl sqrt (double);
_CRTIMP double __cdecl ceil (double);
_CRTIMP double __cdecl floor (double);
@ -156,6 +152,44 @@ _CRTIMP double __cdecl frexp (double, int*);
_CRTIMP double __cdecl modf (double, double*);
_CRTIMP double __cdecl fmod (double, double);
/* Excess precision when using a 64-bit mantissa for FPU math ops can
cause unexpected results with some of the MSVCRT math functions. For
example, unless the function return value is stored (truncating to
53-bit mantissa), calls to pow with both x and y as integral values
sometimes produce a non-integral result.
One workaround is to reset the FPU env to 53-bit mantissa
by a call to fesetenv (FE_PC53_ENV). Amother is to force storage
of the return value of individual math functions using wrappers.
NB, using these wrappers will disable builtin math functions and
hence disable the folding of function results at compile time when
arguments are constant. */
#if 0
#define __DEFINE_FLOAT_STORE_MATHFN_D1(fn1) \
static __inline__ double \
__float_store_ ## fn1 (double x) \
{ \
__volatile__ double res = (fn1) (x); \
return res; \
}
#define __DEFINE_FLOAT_STORE_MATHFN_D2(fn2) \
static __inline__ double \
__float_store_ ## fn2 (double x, double y) \
{ \
__volatile__ double res = (fn2) (x, y); \
return res; \
}
#endif
/* For example, here is how to force the result of the pow function
to be stored: */
#if 0
#undef pow
/* Define the ___float_store_pow function and use it instead of pow(). */
__DEFINE_FLOAT_STORE_MATHFN_D2 (pow)
#define pow __float_store_pow
#endif
#ifndef __STRICT_ANSI__