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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /modules/fdlibm/src/s_tanh.cpp
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'modules/fdlibm/src/s_tanh.cpp')
-rw-r--r--modules/fdlibm/src/s_tanh.cpp79
1 files changed, 79 insertions, 0 deletions
diff --git a/modules/fdlibm/src/s_tanh.cpp b/modules/fdlibm/src/s_tanh.cpp
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+/* @(#)s_tanh.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.
+ * ====================================================
+ */
+
+//#include <sys/cdefs.h>
+//__FBSDID("$FreeBSD$");
+
+/* Tanh(x)
+ * Return the Hyperbolic Tangent of x
+ *
+ * Method :
+ * x -x
+ * e - e
+ * 0. tanh(x) is defined to be -----------
+ * x -x
+ * e + e
+ * 1. reduce x to non-negative by tanh(-x) = -tanh(x).
+ * 2. 0 <= x < 2**-28 : tanh(x) := x with inexact if x != 0
+ * -t
+ * 2**-28 <= x < 1 : tanh(x) := -----; t = expm1(-2x)
+ * t + 2
+ * 2
+ * 1 <= x < 22 : tanh(x) := 1 - -----; t = expm1(2x)
+ * t + 2
+ * 22 <= x <= INF : tanh(x) := 1.
+ *
+ * Special cases:
+ * tanh(NaN) is NaN;
+ * only tanh(0)=0 is exact for finite argument.
+ */
+
+#include <float.h>
+
+#include "math_private.h"
+
+static const volatile double tiny = 1.0e-300;
+static const double one = 1.0, two = 2.0, huge = 1.0e300;
+
+double
+tanh(double x)
+{
+ double t,z;
+ int32_t jx,ix;
+
+ GET_HIGH_WORD(jx,x);
+ ix = jx&0x7fffffff;
+
+ /* x is INF or NaN */
+ if(ix>=0x7ff00000) {
+ if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */
+ else return one/x-one; /* tanh(NaN) = NaN */
+ }
+
+ /* |x| < 22 */
+ if (ix < 0x40360000) { /* |x|<22 */
+ if (ix<0x3e300000) { /* |x|<2**-28 */
+ if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */
+ }
+ if (ix>=0x3ff00000) { /* |x|>=1 */
+ t = expm1(two*fabs(x));
+ z = one - two/(t+two);
+ } else {
+ t = expm1(-two*fabs(x));
+ z= -t/(t+two);
+ }
+ /* |x| >= 22, return +-1 */
+ } else {
+ z = one - tiny; /* raise inexact flag */
+ }
+ return (jx>=0)? z: -z;
+}