math.h

是关于变结构控制的一个简单实例

/***
*math.h - definitions and declarations for math library
*
*       Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This file contains constant definitions and external subroutine
*       declarations for the math subroutine library.
*       [ANSI/System V]
*
*       [Public]
*
****/

#if     _MSC_VER > 1000
#pragma once
#endif

#ifndef _INC_MATH
#define _INC_MATH

#if     !defined(_WIN32) && !defined(_MAC)
#error ERROR: Only Mac or Win32 targets supported!
#endif


#ifdef  _MSC_VER
/*
 * Currently, all MS C compilers for Win32 platforms default to 8 byte
 * alignment.
 */
#pragma pack(push,8)
#endif  /* _MSC_VER */

#ifdef __cplusplus
extern "C" {
#endif

#ifndef __assembler /* Protect from assembler */

/* Define _CRTIMP */

#ifndef _CRTIMP
#ifdef  _DLL
#define _CRTIMP __declspec(dllimport)
#else   /* ndef _DLL */
#define _CRTIMP
#endif  /* _DLL */
#endif  /* _CRTIMP */


/* Define __cdecl for non-Microsoft compilers */

#if     ( !defined(_MSC_VER) && !defined(__cdecl) )
#define __cdecl
#endif

/* Define _CRTAPI1 (for compatibility with the NT SDK) */

#ifndef _CRTAPI1
#if	_MSC_VER >= 800 && _M_IX86 >= 300
#define _CRTAPI1 __cdecl
#else
#define _CRTAPI1
#endif
#endif


/* Definition of _exception struct - this struct is passed to the matherr
 * routine when a floating point exception is detected
 */

#ifndef _EXCEPTION_DEFINED
struct _exception {
        int type;       /* exception type - see below */
        char *name;     /* name of function where error occured */
        double arg1;    /* first argument to function */
        double arg2;    /* second argument (if any) to function */
        double retval;  /* value to be returned by function */
        } ;

#define _EXCEPTION_DEFINED
#endif


/* Definition of a _complex struct to be used by those who use cabs and
 * want type checking on their argument
 */

#ifndef _COMPLEX_DEFINED
struct _complex {
        double x,y; /* real and imaginary parts */
        } ;

#if     !__STDC__ && !defined (__cplusplus)
/* Non-ANSI name for compatibility */
#define complex _complex
#endif

#define _COMPLEX_DEFINED
#endif
#endif  /* __assembler */


/* Constant definitions for the exception type passed in the _exception struct
 */

#define _DOMAIN     1   /* argument domain error */
#define _SING       2   /* argument singularity */
#define _OVERFLOW   3   /* overflow range error */
#define _UNDERFLOW  4   /* underflow range error */
#define _TLOSS      5   /* total loss of precision */
#define _PLOSS      6   /* partial loss of precision */

#define EDOM        33
#define ERANGE      34


/* Definitions of _HUGE and HUGE_VAL - respectively the XENIX and ANSI names
 * for a value returned in case of error by a number of the floating point
 * math routines
 */
#ifndef __assembler /* Protect from assembler */
_CRTIMP extern double _HUGE;
#endif  /* __assembler */

#define HUGE_VAL _HUGE


/* Function prototypes */

#if     !defined(__assembler)   /* Protect from assembler */
#if     _M_MRX000
_CRTIMP int     __cdecl abs(int);
_CRTIMP double  __cdecl acos(double);
_CRTIMP double  __cdecl asin(double);
_CRTIMP double  __cdecl atan(double);
_CRTIMP double  __cdecl atan2(double, double);
_CRTIMP double  __cdecl cos(double);
_CRTIMP double  __cdecl cosh(double);
_CRTIMP double  __cdecl exp(double);
_CRTIMP double  __cdecl fabs(double);
_CRTIMP double  __cdecl fmod(double, double);
_CRTIMP long    __cdecl labs(long);
_CRTIMP double  __cdecl log(double);
_CRTIMP double  __cdecl log10(double);
_CRTIMP double  __cdecl pow(double, double);
_CRTIMP double  __cdecl sin(double);
_CRTIMP double  __cdecl sinh(double);
_CRTIMP double  __cdecl tan(double);
_CRTIMP double  __cdecl tanh(double);
_CRTIMP double  __cdecl sqrt(double);
#else
        int     __cdecl abs(int);
        double  __cdecl acos(double);
        double  __cdecl asin(double);
        double  __cdecl atan(double);
        double  __cdecl atan2(double, double);
        double  __cdecl cos(double);
        double  __cdecl cosh(double);
        double  __cdecl exp(double);
        double  __cdecl fabs(double);
        double  __cdecl fmod(double, double);
        long    __cdecl labs(long);
        double  __cdecl log(double);
        double  __cdecl log10(double);
        double  __cdecl pow(double, double);
        double  __cdecl sin(double);
        double  __cdecl sinh(double);
        double  __cdecl tan(double);
        double  __cdecl tanh(double);
        double  __cdecl sqrt(double);
#endif
_CRTIMP double  __cdecl atof(const char *);
_CRTIMP double  __cdecl _cabs(struct _complex);
#if     defined(_M_ALPHA)
        double  __cdecl ceil(double);
        double  __cdecl floor(double);
#else
_CRTIMP double  __cdecl ceil(double);
_CRTIMP double  __cdecl floor(double);
#endif
_CRTIMP double  __cdecl frexp(double, int *);
_CRTIMP double  __cdecl _hypot(double, double);
_CRTIMP double  __cdecl _j0(double);
_CRTIMP double  __cdecl _j1(double);
_CRTIMP double  __cdecl _jn(int, double);
_CRTIMP double  __cdecl ldexp(double, int);
        int     __cdecl _matherr(struct _exception *);
_CRTIMP double  __cdecl modf(double, double *);

_CRTIMP double  __cdecl _y0(double);
_CRTIMP double  __cdecl _y1(double);
_CRTIMP double  __cdecl _yn(int, double);


#if     defined(_M_MRX000)

/* MIPS fast prototypes for float */
/* ANSI C, 4.5 Mathematics        */

/* 4.5.2 Trigonometric functions */

_CRTIMP float  __cdecl acosf( float );
_CRTIMP float  __cdecl asinf( float );
_CRTIMP float  __cdecl atanf( float );
_CRTIMP float  __cdecl atan2f( float , float );
_CRTIMP float  __cdecl cosf( float );
_CRTIMP float  __cdecl sinf( float );
_CRTIMP float  __cdecl tanf( float );

/* 4.5.3 Hyperbolic functions */
_CRTIMP float  __cdecl coshf( float );
_CRTIMP float  __cdecl sinhf( float );
_CRTIMP float  __cdecl tanhf( float );

/* 4.5.4 Exponential and logarithmic functions */
_CRTIMP float  __cdecl expf( float );
_CRTIMP float  __cdecl logf( float );
_CRTIMP float  __cdecl log10f( float );
_CRTIMP float  __cdecl modff( float , float* );

/* 4.5.5 Power functions */
_CRTIMP float  __cdecl powf( float , float );
        float  __cdecl sqrtf( float );

/* 4.5.6 Nearest integer, absolute value, and remainder functions */
        float  __cdecl ceilf( float );
        float  __cdecl fabsf( float );
        float  __cdecl floorf( float );
_CRTIMP float  __cdecl fmodf( float , float );

_CRTIMP float  __cdecl hypotf(float, float);

#endif  /* _M_MRX000 */

#if     defined(_M_ALPHA)

/* ALPHA fast prototypes for float */
/* ANSI C, 4.5 Mathematics        */

/* 4.5.2 Trigonometric functions */

        float  __cdecl acosf( float );
        float  __cdecl asinf( float );
        float  __cdecl atanf( float );
        float  __cdecl atan2f( float , float );
        float  __cdecl cosf( float );
        float  __cdecl sinf( float );
        float  __cdecl tanf( float );

/* 4.5.3 Hyperbolic functions */
        float  __cdecl coshf( float );
        float  __cdecl sinhf( float );
        float  __cdecl tanhf( float );

/* 4.5.4 Exponential and logarithmic functions */
        float  __cdecl expf( float );
        float  __cdecl logf( float );
        float  __cdecl log10f( float );
_CRTIMP float  __cdecl modff( float , float* );

/* 4.5.5 Power functions */
        float  __cdecl powf( float , float );
        float  __cdecl sqrtf( float );

/* 4.5.6 Nearest integer, absolute value, and remainder functions */
        float  __cdecl ceilf( float );
        float  __cdecl fabsf( float );
        float  __cdecl floorf( float );
        float  __cdecl fmodf( float , float );

_CRTIMP float  __cdecl _hypotf(float, float);

#endif  /* _M_ALPHA */

#if     !defined(_M_M68K)
/* Macros defining long double functions to be their double counterparts
 * (long double is synonymous with double in this implementation).
 */


#ifndef __cplusplus
#define acosl(x)    ((long double)acos((double)(x)))
#define asinl(x)    ((long double)asin((double)(x)))
#define atanl(x)    ((long double)atan((double)(x)))
#define atan2l(x,y) ((long double)atan2((double)(x), (double)(y)))
#define _cabsl      _cabs
#define ceill(x)    ((long double)ceil((double)(x)))
#define cosl(x)     ((long double)cos((double)(x)))
#define coshl(x)    ((long double)cosh((double)(x)))
#define expl(x)     ((long double)exp((double)(x)))
#define fabsl(x)    ((long double)fabs((double)(x)))
#define floorl(x)   ((long double)floor((double)(x)))
#define fmodl(x,y)  ((long double)fmod((double)(x), (double)(y)))
#define frexpl(x,y) ((long double)frexp((double)(x), (y)))
#define _hypotl(x,y)    ((long double)_hypot((double)(x), (double)(y)))
#define ldexpl(x,y) ((long double)ldexp((double)(x), (y)))
#define logl(x)     ((long double)log((double)(x)))
#define log10l(x)   ((long double)log10((double)(x)))
#define _matherrl   _matherr
#define modfl(x,y)  ((long double)modf((double)(x), (double *)(y)))
#define powl(x,y)   ((long double)pow((double)(x), (double)(y)))
#define sinl(x)     ((long double)sin((double)(x)))
#define sinhl(x)    ((long double)sinh((double)(x)))
#define sqrtl(x)    ((long double)sqrt((double)(x)))
#define tanl(x)     ((long double)tan((double)(x)))
#define tanhl(x)    ((long double)tanh((double)(x)))
#else   /* __cplusplus */
inline long double acosl(long double _X)
        {return (acos((double)_X)); }
inline long double asinl(long double _X)
        {return (asin((double)_X)); }
inline long double atanl(long double _X)
        {return (atan((double)_X)); }
inline long double atan2l(long double _X, long double _Y)
        {return (atan2((double)_X, (double)_Y)); }
inline long double ceill(long double _X)
        {return (ceil((double)_X)); }
inline long double cosl(long double _X)
        {return (cos((double)_X)); }
inline long double coshl(long double _X)