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| /* @(#)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 |
| |
| ANSI_SYNOPSIS |
| #include <math.h> |
| double acosh(double <[x]>); |
| float acoshf(float <[x]>); |
| |
| TRAD_SYNOPSIS |
| #include <math.h> |
| double acosh(<[x]>) |
| double <[x]>; |
| |
| float acoshf(<[x]>) |
| 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>>. |
| |
| You can change the error-handling behavior with the non-ANSI |
| <<matherr>> function. |
| |
| PORTABILITY |
| Neither <<acosh>> nor <<acoshf>> are ANSI C. They are not recommended |
| for portable programs. |
| |
| |
| QUICKREF ANSI SVID POSIX RENTRANT |
| acos n,n,n,m |
| acosf n,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; |
| struct exception exc; |
| z = __ieee754_acosh(x); |
| if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
| if(x<1.0) { |
| /* acosh(x<1) */ |
| exc.type = DOMAIN; |
| exc.name = "acosh"; |
| exc.err = 0; |
| exc.arg1 = exc.arg2 = x; |
| exc.retval = 0.0/0.0; |
| if (_LIB_VERSION == _POSIX_) |
| errno = EDOM; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } else |
| return z; |
| #endif |
| } |
| |
| #endif /* defined(_DOUBLE_IS_32BITS) */ |