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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [math/] [w_pow.c] - Rev 617
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/* @(#)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 powf(float <[x]>, float <[y]>); TRAD_SYNOPSIS #include <math.h> double pow(<[x]>, <[y]>); double <[x]>, <[y]>; float powf(<[x]>, <[y]>); float <[x]>, <[y]>; DESCRIPTION <<pow>> and <<powf>> calculate <[x]> raised to the exponent <[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 = 1.0; 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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