forked from xuos/xiuos
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/* Copyright JS Foundation and other contributors, http://js.foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is based on work under the following copyright and permission
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* notice:
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*
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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*
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* @(#)e_sinh.c 1.3 95/01/18
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*/
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#include "jerry-math-internal.h"
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/* __sinh(x)
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* Method:
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* mathematically sinh(x) if defined to be (exp(x) - exp(-x)) / 2
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* 1. Replace x by |x| (sinh(-x) = -sinh(x)).
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* 2.
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* E + E/(E+1)
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* 0 <= x <= 22 : sinh(x) := -------------, E = expm1(x)
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* 2
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*
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* 22 <= x <= lnovft : sinh(x) := exp(x) / 2
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* lnovft <= x <= ln2ovft: sinh(x) := exp(x / 2) / 2 * exp(x / 2)
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* ln2ovft < x : sinh(x) := x * shuge (overflow)
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*
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* Special cases:
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* sinh(x) is |x| if x is +INF, -INF, or NaN.
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* only sinh(0) = 0 is exact for finite x.
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*/
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#define one 1.0
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#define half 0.5
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#define shuge 1.0e307
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double
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sinh (double x)
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{
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double t, w, h;
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int ix, jx;
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unsigned lx;
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/* High word of |x|. */
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jx = __HI (x);
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ix = jx & 0x7fffffff;
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/* x is INF or NaN */
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if (ix >= 0x7ff00000)
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{
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return x + x;
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}
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h = 0.5;
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if (jx < 0)
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{
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h = -h;
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}
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/* |x| in [0,22], return sign(x) * 0.5 * (E + E / (E + 1))) */
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if (ix < 0x40360000)
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{
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/* |x| < 22 */
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if (ix < 0x3e300000)
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{
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/* |x| < 2**-28 */
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if (shuge + x > one)
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{
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/* sinh(tiny) = tiny with inexact */
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return x;
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}
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}
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t = expm1 (fabs (x));
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if (ix < 0x3ff00000)
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{
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return h * (2.0 * t - t * t / (t + one));
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}
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return h * (t + t / (t + one));
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}
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/* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
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if (ix < 0x40862E42)
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{
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return h * exp (fabs (x));
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}
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/* |x| in [log(maxdouble), overflowthresold] */
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lx = ((1 >> 29) + (unsigned int) x);
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if (ix < 0x408633CE || ((ix == 0x408633ce) && (lx <= (unsigned) 0x8fb9f87d)))
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{
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w = exp (0.5 * fabs (x));
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t = h * w;
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return t * w;
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}
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/* |x| > overflowthresold, sinh(x) overflow */
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return x * shuge;
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} /* sinh */
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#undef one
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#undef half
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#undef huge
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