/* @(#)w_acosh.c 5.1 93/09/24 */ /* * ==================================================== * 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 <<acosh>>, <<acoshf>>---inverse hyperbolic cosine INDEX acosh INDEX acoshf SYNOPSIS #include <math.h> double acosh(double <[x]>); float acoshf(float <[x]>); DESCRIPTION <<acosh>> calculates the inverse hyperbolic cosine of <[x]>. <<acosh>> is defined as @ifnottex . log(<[x]> + sqrt(<[x]>*<[x]>-1)) @end ifnottex @tex $$ln\Bigl(x + \sqrt{x^2-1}\Bigr)$$ @end tex <[x]> must be a number greater than or equal to 1. <<acoshf>> is identical, other than taking and returning floats. RETURNS <<acosh>> and <<acoshf>> return the calculated value. If <[x]> less than 1, the return value is NaN and <<errno>> is set to <<EDOM>>. PORTABILITY Neither <<acosh>> nor <<acoshf>> are ANSI C. They are not recommended for portable programs. QUICKREF ansi posix rentrant acos n,n,m acosf n,n,m MATHREF acosh, NAN, arg,DOMAIN,EDOM acosh, < 1.0, NAN,DOMAIN,EDOM acosh, >=1.0, acosh(arg),,, MATHREF acoshf, NAN, arg,DOMAIN,EDOM acoshf, < 1.0, NAN,DOMAIN,EDOM acoshf, >=1.0, acosh(arg),,, */ /* * wrapper acosh(x) */ #include "fdlibm.h" #include <errno.h> #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ double acosh(double x) /* wrapper acosh */ #else double acosh(x) /* wrapper acosh */ double x; #endif { #ifdef _IEEE_LIBM return __ieee754_acosh(x); #else double z; z = __ieee754_acosh(x); if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; if(x<1.0) { /* acosh(x<1) */ errno = EDOM; return 0.0/0.0; } else return z; #endif } #endif /* defined(_DOUBLE_IS_32BITS) */