Include/pymath.h

   1 #ifndef Py_PYMATH_H
   2 #define Py_PYMATH_H
   3
   4 #include "pyconfig.h" /* include for defines */
   5
   6 /**************************************************************************
   7 Symbols and macros to supply platform-independent interfaces to mathematical
   8 functions and constants
   9 **************************************************************************/
  10
  11 /* Python provides implementations for copysign, round and hypot in
  12  * Python/pymath.c just in case your math library doesn't provide the
  13  * functions.
  14  *
  15  *Note: PC/pyconfig.h defines copysign as _copysign
  16  */
  17 #ifndef HAVE_COPYSIGN
  18 extern double copysign(double, double);
  19 #endif
  20
  21 #ifndef HAVE_ROUND
  22 extern double round(double);
  23 #endif
  24
  25 #ifndef HAVE_HYPOT
  26 extern double hypot(double, double);
  27 #endif
  28
  29 /* extra declarations */
  30 #ifndef _MSC_VER
  31 #ifndef __STDC__
  32 extern double fmod (double, double);
  33 extern double frexp (double, int *);
  34 extern double ldexp (double, int);
  35 extern double modf (double, double *);
  36 extern double pow(double, double);
  37 #endif /* __STDC__ */
  38 #endif /* _MSC_VER */
  39
  40 #ifdef _OSF_SOURCE
  41 /* OSF1 5.1 doesn't make these available with XOPEN_SOURCE_EXTENDED defined */
  42 extern int finite(double);
  43 extern double copysign(double, double);
  44 #endif
  45
  46 /* High precision defintion of pi and e (Euler)
  47  * The values are taken from libc6's math.h.
  48  */
  49 #ifndef Py_MATH_PIl
  50 #define Py_MATH_PIl 3.1415926535897932384626433832795029L
  51 #endif
  52 #ifndef Py_MATH_PI
  53 #define Py_MATH_PI 3.14159265358979323846
  54 #endif
  55
  56 #ifndef Py_MATH_El
  57 #define Py_MATH_El 2.7182818284590452353602874713526625L
  58 #endif
  59
  60 #ifndef Py_MATH_E
  61 #define Py_MATH_E 2.7182818284590452354
  62 #endif
  63
  64 /* On x86, Py_FORCE_DOUBLE forces a floating-point number out of an x87 FPU
  65    register and into a 64-bit memory location, rounding from extended
  66    precision to double precision in the process.  On other platforms it does
  67    nothing. */
  68
  69 /* we take double rounding as evidence of x87 usage */
  70 #ifndef Py_FORCE_DOUBLE
  71 #  ifdef X87_DOUBLE_ROUNDING
  72 PyAPI_FUNC(double) _Py_force_double(double);
  73 #    define Py_FORCE_DOUBLE(X) (_Py_force_double(X))
  74 #  else
  75 #    define Py_FORCE_DOUBLE(X) (X)
  76 #  endif
  77 #endif
  78
  79 #ifdef HAVE_GCC_ASM_FOR_X87
  80 PyAPI_FUNC(unsigned short) _Py_get_387controlword(void);
  81 PyAPI_FUNC(void) _Py_set_387controlword(unsigned short);
  82 #endif
  83
  84 /* Py_IS_NAN(X)
  85  * Return 1 if float or double arg is a NaN, else 0.
  86  * Caution:
  87  *     X is evaluated more than once.
  88  *     This may not work on all platforms.  Each platform has *some*
  89  *     way to spell this, though -- override in pyconfig.h if you have
  90  *     a platform where it doesn't work.
  91  * Note: PC/pyconfig.h defines Py_IS_NAN as _isnan
  92  */
  93 #ifndef Py_IS_NAN
  94 #if defined HAVE_DECL_ISNAN && HAVE_DECL_ISNAN == 1
  95 #define Py_IS_NAN(X) isnan(X)
  96 #else
  97 #define Py_IS_NAN(X) ((X) != (X))
  98 #endif
  99 #endif
 100
 101 /* Py_IS_INFINITY(X)
 102  * Return 1 if float or double arg is an infinity, else 0.
 103  * Caution:
 104  *    X is evaluated more than once.
 105  *    This implementation may set the underflow flag if |X| is very small;
 106  *    it really can't be implemented correctly (& easily) before C99.
 107  *    Override in pyconfig.h if you have a better spelling on your platform.
 108  *  Py_FORCE_DOUBLE is used to avoid getting false negatives from a
 109  *    non-infinite value v sitting in an 80-bit x87 register such that
 110  *    v becomes infinite when spilled from the register to 64-bit memory.
 111  * Note: PC/pyconfig.h defines Py_IS_INFINITY as _isinf
 112  */
 113 #ifndef Py_IS_INFINITY
 114 #  if defined HAVE_DECL_ISINF && HAVE_DECL_ISINF == 1
 115 #    define Py_IS_INFINITY(X) isinf(X)
 116 #  else
 117 #    define Py_IS_INFINITY(X) ((X) &&                                   \
 118                                (Py_FORCE_DOUBLE(X)*0.5 == Py_FORCE_DOUBLE(X)))
 119 #  endif
 120 #endif
 121
 122 /* Py_IS_FINITE(X)
 123  * Return 1 if float or double arg is neither infinite nor NAN, else 0.
 124  * Some compilers (e.g. VisualStudio) have intrisics for this, so a special
 125  * macro for this particular test is useful
 126  * Note: PC/pyconfig.h defines Py_IS_FINITE as _finite
 127  */
 128 #ifndef Py_IS_FINITE
 129 #if defined HAVE_DECL_ISFINITE && HAVE_DECL_ISFINITE == 1
 130 #define Py_IS_FINITE(X) isfinite(X)
 131 #elif defined HAVE_FINITE
 132 #define Py_IS_FINITE(X) finite(X)
 133 #else
 134 #define Py_IS_FINITE(X) (!Py_IS_INFINITY(X) && !Py_IS_NAN(X))
 135 #endif
 136 #endif
 137
 138 /* HUGE_VAL is supposed to expand to a positive double infinity.  Python
 139  * uses Py_HUGE_VAL instead because some platforms are broken in this
 140  * respect.  We used to embed code in pyport.h to try to worm around that,
 141  * but different platforms are broken in conflicting ways.  If you're on
 142  * a platform where HUGE_VAL is defined incorrectly, fiddle your Python
 143  * config to #define Py_HUGE_VAL to something that works on your platform.
 144  */
 145 #ifndef Py_HUGE_VAL
 146 #define Py_HUGE_VAL HUGE_VAL
 147 #endif
 148
 149 /* Py_NAN
 150  * A value that evaluates to a NaN. On IEEE 754 platforms INF*0 or
 151  * INF/INF works. Define Py_NO_NAN in pyconfig.h if your platform
 152  * doesn't support NaNs.
 153  */
 154 #if !defined(Py_NAN) && !defined(Py_NO_NAN)
 155 #define Py_NAN (Py_HUGE_VAL * 0.)
 156 #endif
 157
 158 /* Py_OVERFLOWED(X)
 159  * Return 1 iff a libm function overflowed.  Set errno to 0 before calling
 160  * a libm function, and invoke this macro after, passing the function
 161  * result.
 162  * Caution:
 163  *    This isn't reliable.  C99 no longer requires libm to set errno under
 164  *        any exceptional condition, but does require +- HUGE_VAL return
 165  *        values on overflow.  A 754 box *probably* maps HUGE_VAL to a
 166  *        double infinity, and we're cool if that's so, unless the input
 167  *        was an infinity and an infinity is the expected result.  A C89
 168  *        system sets errno to ERANGE, so we check for that too.  We're
 169  *        out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or
 170  *        if the returned result is a NaN, or if a C89 box returns HUGE_VAL
 171  *        in non-overflow cases.
 172  *    X is evaluated more than once.
 173  * Some platforms have better way to spell this, so expect some #ifdef'ery.
 174  *
 175  * OpenBSD uses 'isinf()' because a compiler bug on that platform causes
 176  * the longer macro version to be mis-compiled. This isn't optimal, and
 177  * should be removed once a newer compiler is available on that platform.
 178  * The system that had the failure was running OpenBSD 3.2 on Intel, with
 179  * gcc 2.95.3.
 180  *
 181  * According to Tim's checkin, the FreeBSD systems use isinf() to work
 182  * around a FPE bug on that platform.
 183  */
 184 #if defined(__FreeBSD__) || defined(__OpenBSD__)
 185 #define Py_OVERFLOWED(X) isinf(X)
 186 #else
 187 #define Py_OVERFLOWED(X) ((X) != 0.0 && (errno == ERANGE ||    \
 188                                          (X) == Py_HUGE_VAL || \
 189                                          (X) == -Py_HUGE_VAL))
 190 #endif
 191
 192 #endif /* Py_PYMATH_H */