1 /* 2 * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* __ieee754_sinh(x) 27 * Method : 28 * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2 29 * 1. Replace x by |x| (sinh(-x) = -sinh(x)). 30 * 2. 31 * E + E/(E+1) 32 * 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x) 33 * 2 34 * 35 * 22 <= x <= lnovft : sinh(x) := exp(x)/2 36 * lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2) 37 * ln2ovft < x : sinh(x) := x*shuge (overflow) 38 * 39 * Special cases: 40 * sinh(x) is |x| if x is +INF, -INF, or NaN. 41 * only sinh(0)=0 is exact for finite x. 42 */ 43 44 #include "fdlibm.h" 45 46 #ifdef __STDC__ 47 static const double one = 1.0, shuge = 1.0e307; 48 #else 49 static double one = 1.0, shuge = 1.0e307; 50 #endif 51 52 #ifdef __STDC__ __ieee754_sinh(double x)53 double __ieee754_sinh(double x) 54 #else 55 double __ieee754_sinh(x) 56 double x; 57 #endif 58 { 59 double t,w,h; 60 int ix,jx; 61 unsigned lx; 62 63 /* High word of |x|. */ 64 jx = __HI(x); 65 ix = jx&0x7fffffff; 66 67 /* x is INF or NaN */ 68 if(ix>=0x7ff00000) return x+x; 69 70 h = 0.5; 71 if (jx<0) h = -h; 72 /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */ 73 if (ix < 0x40360000) { /* |x|<22 */ 74 if (ix<0x3e300000) /* |x|<2**-28 */ 75 if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */ 76 t = expm1(fabs(x)); 77 if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one)); 78 return h*(t+t/(t+one)); 79 } 80 81 /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */ 82 if (ix < 0x40862E42) return h*__ieee754_exp(fabs(x)); 83 84 /* |x| in [log(maxdouble), overflowthresold] */ 85 lx = *( (((*(unsigned*)&one)>>29)) + (unsigned*)&x); 86 if (ix<0x408633CE || ((ix==0x408633ce)&&(lx<=(unsigned)0x8fb9f87d))) { 87 w = __ieee754_exp(0.5*fabs(x)); 88 t = h*w; 89 return t*w; 90 } 91 92 /* |x| > overflowthresold, sinh(x) overflow */ 93 return x*shuge; 94 } 95