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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
+@ifinfo
+. log(<[x]> + sqrt(<[x]>*<[x]>-1))
+@end ifinfo
+@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) */