text: #ifndef Py_PYMATH_H
  #define Py_PYMATH_H
  
  #include "pyconfig.h" /* include for defines */
  
  /**************************************************************************
  Symbols and macros to supply platform-independent interfaces to mathematical
  functions and constants
  **************************************************************************/
  
  /* Python provides implementations for copysign, round and hypot in
   * Python/pymath.c just in case your math library doesn't provide the
   * functions.
   *
   *Note: PC/pyconfig.h defines copysign as _copysign
   */
  #ifndef HAVE_COPYSIGN
  extern double copysign(double, double);
  #endif
  
  #ifndef HAVE_ROUND
  extern double round(double);
  #endif
  
  #ifndef HAVE_HYPOT
  extern double hypot(double, double);
  #endif
  
  /* extra declarations */
  #ifndef _MSC_VER
  #ifndef __STDC__
  extern double fmod (double, double);
  extern double frexp (double, int *);
  extern double ldexp (double, int);
  extern double modf (double, double *);
  extern double pow(double, double);
  #endif /* __STDC__ */
  #endif /* _MSC_VER */
  
  #ifdef _OSF_SOURCE
  /* OSF1 5.1 doesn't make these available with XOPEN_SOURCE_EXTENDED defined */
  extern int finite(double);
  extern double copysign(double, double);
  #endif
  
  /* High precision defintion of pi and e (Euler)
   * The values are taken from libc6's math.h.
   */
  #ifndef Py_MATH_PIl
  #define Py_MATH_PIl 3.1415926535897932384626433832795029L
  #endif
  #ifndef Py_MATH_PI
  #define Py_MATH_PI 3.14159265358979323846
  #endif
  
  #ifndef Py_MATH_El
  #define Py_MATH_El 2.7182818284590452353602874713526625L
  #endif
  
  #ifndef Py_MATH_E
  #define Py_MATH_E 2.7182818284590452354
  #endif
  
  /* On x86, Py_FORCE_DOUBLE forces a floating-point number out of an x87 FPU
     register and into a 64-bit memory location, rounding from extended
     precision to double precision in the process.  On other platforms it does
     nothing. */
  
  /* we take double rounding as evidence of x87 usage */
  #ifndef Py_LIMITED_API
  #ifndef Py_FORCE_DOUBLE
  #  ifdef X87_DOUBLE_ROUNDING
  PyAPI_FUNC(double) _Py_force_double(double);
  #    define Py_FORCE_DOUBLE(X) (_Py_force_double(X))
  #  else
  #    define Py_FORCE_DOUBLE(X) (X)
  #  endif
  #endif
  #endif
  
  #ifndef Py_LIMITED_API
  #ifdef HAVE_GCC_ASM_FOR_X87
  PyAPI_FUNC(unsigned short) _Py_get_387controlword(void);
  PyAPI_FUNC(void) _Py_set_387controlword(unsigned short);
  #endif
  #endif
  
  /* Py_IS_NAN(X)
   * Return 1 if float or double arg is a NaN, else 0.
   * Caution:
   *     X is evaluated more than once.
   *     This may not work on all platforms.  Each platform has *some*
   *     way to spell this, though -- override in pyconfig.h if you have
   *     a platform where it doesn't work.
   * Note: PC/pyconfig.h defines Py_IS_NAN as _isnan
   */
  #ifndef Py_IS_NAN
  #if defined HAVE_DECL_ISNAN && HAVE_DECL_ISNAN == 1
  #define Py_IS_NAN(X) isnan(X)
  #else
  #define Py_IS_NAN(X) ((X) != (X))
  #endif
  #endif
  
  /* Py_IS_INFINITY(X)
   * Return 1 if float or double arg is an infinity, else 0.
   * Caution:
   *    X is evaluated more than once.
   *    This implementation may set the underflow flag if |X| is very small;
   *    it really can't be implemented correctly (& easily) before C99.
   *    Override in pyconfig.h if you have a better spelling on your platform.
   *  Py_FORCE_DOUBLE is used to avoid getting false negatives from a
   *    non-infinite value v sitting in an 80-bit x87 register such that
   *    v becomes infinite when spilled from the register to 64-bit memory.
   * Note: PC/pyconfig.h defines Py_IS_INFINITY as _isinf
   */
  #ifndef Py_IS_INFINITY
  #  if defined HAVE_DECL_ISINF && HAVE_DECL_ISINF == 1
  #    define Py_IS_INFINITY(X) isinf(X)
  #  else
  #    define Py_IS_INFINITY(X) ((X) &&                                   \
                                 (Py_FORCE_DOUBLE(X)*0.5 == Py_FORCE_DOUBLE(X)))
  #  endif
  #endif
  
  /* Py_IS_FINITE(X)
   * Return 1 if float or double arg is neither infinite nor NAN, else 0.
   * Some compilers (e.g. VisualStudio) have intrisics for this, so a special
   * macro for this particular test is useful
   * Note: PC/pyconfig.h defines Py_IS_FINITE as _finite
   */
  #ifndef Py_IS_FINITE
  #if defined HAVE_DECL_ISFINITE && HAVE_DECL_ISFINITE == 1
  #define Py_IS_FINITE(X) isfinite(X)
  #elif defined HAVE_FINITE
  #define Py_IS_FINITE(X) finite(X)
  #else
  #define Py_IS_FINITE(X) (!Py_IS_INFINITY(X) && !Py_IS_NAN(X))
  #endif
  #endif
  
  /* HUGE_VAL is supposed to expand to a positive double infinity.  Python
   * uses Py_HUGE_VAL instead because some platforms are broken in this
   * respect.  We used to embed code in pyport.h to try to worm around that,
   * but different platforms are broken in conflicting ways.  If you're on
   * a platform where HUGE_VAL is defined incorrectly, fiddle your Python
   * config to #define Py_HUGE_VAL to something that works on your platform.
   */
  #ifndef Py_HUGE_VAL
  #define Py_HUGE_VAL HUGE_VAL
  #endif
  
  /* Py_NAN
   * A value that evaluates to a NaN. On IEEE 754 platforms INF*0 or
   * INF/INF works. Define Py_NO_NAN in pyconfig.h if your platform
   * doesn't support NaNs.
   */
  #if !defined(Py_NAN) && !defined(Py_NO_NAN)
  #define Py_NAN (Py_HUGE_VAL * 0.)
  #endif
  
  /* Py_OVERFLOWED(X)
   * Return 1 iff a libm function overflowed.  Set errno to 0 before calling
   * a libm function, and invoke this macro after, passing the function
   * result.
   * Caution:
   *    This isn't reliable.  C99 no longer requires libm to set errno under
   *	  any exceptional condition, but does require +- HUGE_VAL return
   *	  values on overflow.  A 754 box *probably* maps HUGE_VAL to a
   *	  double infinity, and we're cool if that's so, unless the input
   *	  was an infinity and an infinity is the expected result.  A C89
   *	  system sets errno to ERANGE, so we check for that too.  We're
   *	  out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or
   *	  if the returned result is a NaN, or if a C89 box returns HUGE_VAL
   *	  in non-overflow cases.
   *    X is evaluated more than once.
   * Some platforms have better way to spell this, so expect some #ifdef'ery.
   *
   * OpenBSD uses 'isinf()' because a compiler bug on that platform causes
   * the longer macro version to be mis-compiled. This isn't optimal, and
   * should be removed once a newer compiler is available on that platform.
   * The system that had the failure was running OpenBSD 3.2 on Intel, with
   * gcc 2.95.3.
   *
   * According to Tim's checkin, the FreeBSD systems use isinf() to work
   * around a FPE bug on that platform.
   */
  #if defined(__FreeBSD__) || defined(__OpenBSD__)
  #define Py_OVERFLOWED(X) isinf(X)
  #else
  #define Py_OVERFLOWED(X) ((X) != 0.0 && (errno == ERANGE ||    \
  					 (X) == Py_HUGE_VAL || \
  					 (X) == -Py_HUGE_VAL))
  #endif
  
  #endif /* Py_PYMATH_H */
  