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Diffstat (limited to 'sysdeps/generic/tanh.c')
| -rw-r--r-- | sysdeps/generic/tanh.c | 99 |
1 files changed, 0 insertions, 99 deletions
diff --git a/sysdeps/generic/tanh.c b/sysdeps/generic/tanh.c deleted file mode 100644 index d4923b3418..0000000000 --- a/sysdeps/generic/tanh.c +++ /dev/null @@ -1,99 +0,0 @@ -/* - * Copyright (c) 1985, 1993 - * The Regents of the University of California. All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. All advertising materials mentioning features or use of this software - * must display the following acknowledgement: - * This product includes software developed by the University of - * California, Berkeley and its contributors. - * 4. Neither the name of the University nor the names of its contributors - * may be used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - */ - -#ifndef lint -static char sccsid[] = "@(#)tanh.c 8.1 (Berkeley) 6/4/93"; -#endif /* not lint */ - -/* TANH(X) - * RETURN THE HYPERBOLIC TANGENT OF X - * DOUBLE PRECISION (VAX D FORMAT 56 BITS, IEEE DOUBLE 53 BITS) - * CODED IN C BY K.C. NG, 1/8/85; - * REVISED BY K.C. NG on 2/8/85, 2/11/85, 3/7/85, 3/24/85. - * - * Required system supported functions : - * copysign(x,y) - * finite(x) - * - * Required kernel function: - * expm1(x) ...exp(x)-1 - * - * Method : - * 1. reduce x to non-negative by tanh(-x) = - tanh(x). - * 2. - * 0 < x <= 1.e-10 : tanh(x) := x - * -expm1(-2x) - * 1.e-10 < x <= 1 : tanh(x) := -------------- - * expm1(-2x) + 2 - * 2 - * 1 <= x <= 22.0 : tanh(x) := 1 - --------------- - * expm1(2x) + 2 - * 22.0 < x <= INF : tanh(x) := 1. - * - * Note: 22 was chosen so that fl(1.0+2/(expm1(2*22)+2)) == 1. - * - * Special cases: - * tanh(NaN) is NaN; - * only tanh(0)=0 is exact for finite argument. - * - * Accuracy: - * tanh(x) returns the exact hyperbolic tangent of x nealy rounded. - * In a test run with 1,024,000 random arguments on a VAX, the maximum - * observed error was 2.22 ulps (units in the last place). - */ - -double tanh(x) -double x; -{ - static double one=1.0, two=2.0, small = 1.0e-10, big = 1.0e10; - double expm1(), t, copysign(), sign; - int finite(); - -#if !defined(vax)&&!defined(tahoe) - if(x!=x) return(x); /* x is NaN */ -#endif /* !defined(vax)&&!defined(tahoe) */ - - sign=copysign(one,x); - x=copysign(x,one); - if(x < 22.0) - if( x > one ) - return(copysign(one-two/(expm1(x+x)+two),sign)); - else if ( x > small ) - {t= -expm1(-(x+x)); return(copysign(t/(two-t),sign));} - else /* raise the INEXACT flag for non-zero x */ - {big+x; return(copysign(x,sign));} - else if(finite(x)) - return (sign+1.0E-37); /* raise the INEXACT flag */ - else - return(sign); /* x is +- INF */ -} |