| |
| |
| /* @(#)w_pow.c 5.2 93/10/01 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| /* |
| FUNCTION |
| <<pow>>, <<powf>>---x to the power y |
| INDEX |
| pow |
| INDEX |
| powf |
| |
| |
| ANSI_SYNOPSIS |
| #include <math.h> |
| double pow(double <[x]>, double <[y]>); |
| float pow(float <[x]>, float <[y]>); |
| |
| TRAD_SYNOPSIS |
| #include <math.h> |
| double pow(<[x]>, <[y]>); |
| double <[x]>, <[y]>; |
| |
| float pow(<[x]>, <[y]>); |
| float <[x]>, <[y]>; |
| |
| DESCRIPTION |
| <<pow>> and <<powf>> calculate <[x]> raised to the exp1.0nt <[y]>. |
| @tex |
| (That is, $x^y$.) |
| @end tex |
| |
| RETURNS |
| On success, <<pow>> and <<powf>> return the value calculated. |
| |
| When the argument values would produce overflow, <<pow>> |
| returns <<HUGE_VAL>> and set <<errno>> to <<ERANGE>>. If the |
| argument <[x]> passed to <<pow>> or <<powf>> is a negative |
| noninteger, and <[y]> is also not an integer, then <<errno>> |
| is set to <<EDOM>>. If <[x]> and <[y]> are both 0, then |
| <<pow>> and <<powf>> return <<1>>. |
| |
| You can modify error handling for these functions using <<matherr>>. |
| |
| PORTABILITY |
| <<pow>> is ANSI C. <<powf>> is an extension. */ |
| |
| /* |
| * wrapper pow(x,y) return x**y |
| */ |
| |
| #include "fdlibm.h" |
| #include <errno.h> |
| |
| #ifndef _DOUBLE_IS_32BITS |
| |
| #ifdef __STDC__ |
| double pow(double x, double y) /* wrapper pow */ |
| #else |
| double pow(x,y) /* wrapper pow */ |
| double x,y; |
| #endif |
| { |
| #ifdef _IEEE_LIBM |
| return __ieee754_pow(x,y); |
| #else |
| double z; |
| #ifndef HUGE_VAL |
| #define HUGE_VAL inf |
| double inf = 0.0; |
| |
| SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
| #endif |
| struct exception exc; |
| z=__ieee754_pow(x,y); |
| if(_LIB_VERSION == _IEEE_|| isnan(y)) return z; |
| if(isnan(x)) { |
| if(y==0.0) { |
| /* pow(NaN,0.0) */ |
| /* error only if _LIB_VERSION == _SVID_ & _XOPEN_ */ |
| exc.type = DOMAIN; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| exc.retval = x; |
| if (_LIB_VERSION == _IEEE_ || |
| _LIB_VERSION == _POSIX_) exc.retval = 1.0; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } else |
| return z; |
| } |
| if(x==0.0){ |
| if(y==0.0) { |
| /* pow(0.0,0.0) */ |
| /* error only if _LIB_VERSION == _SVID_ */ |
| exc.type = DOMAIN; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| exc.retval = 0.0; |
| if (_LIB_VERSION != _SVID_) exc.retval = 1.0; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } |
| if(finite(y)&&y<0.0) { |
| /* 0**neg */ |
| exc.type = DOMAIN; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| if (_LIB_VERSION == _SVID_) |
| exc.retval = 0.0; |
| else |
| exc.retval = -HUGE_VAL; |
| if (_LIB_VERSION == _POSIX_) |
| errno = EDOM; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } |
| return z; |
| } |
| if(!finite(z)) { |
| if(finite(x)&&finite(y)) { |
| if(isnan(z)) { |
| /* neg**non-integral */ |
| exc.type = DOMAIN; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| if (_LIB_VERSION == _SVID_) |
| exc.retval = 0.0; |
| else |
| exc.retval = 0.0/0.0; /* X/Open allow NaN */ |
| if (_LIB_VERSION == _POSIX_) |
| errno = EDOM; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } else { |
| /* pow(x,y) overflow */ |
| exc.type = OVERFLOW; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| if (_LIB_VERSION == _SVID_) { |
| exc.retval = HUGE; |
| y *= 0.5; |
| if(x<0.0&&rint(y)!=y) exc.retval = -HUGE; |
| } else { |
| exc.retval = HUGE_VAL; |
| y *= 0.5; |
| if(x<0.0&&rint(y)!=y) exc.retval = -HUGE_VAL; |
| } |
| if (_LIB_VERSION == _POSIX_) |
| errno = ERANGE; |
| else if (!matherr(&exc)) { |
| errno = ERANGE; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } |
| } |
| } |
| if(z==0.0&&finite(x)&&finite(y)) { |
| /* pow(x,y) underflow */ |
| exc.type = UNDERFLOW; |
| exc.name = "pow"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = y; |
| exc.retval = 0.0; |
| if (_LIB_VERSION == _POSIX_) |
| errno = ERANGE; |
| else if (!matherr(&exc)) { |
| errno = ERANGE; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } |
| return z; |
| #endif |
| } |
| |
| #endif /* defined(_DOUBLE_IS_32BITS) */ |
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