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- /*
- * ====================================================
- * 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.
- * ====================================================
- */
- /* __ieee754_sinh(x)
- * Method :
- * mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
- * 1. Replace x by |x| (sinh(-x) = -sinh(x)).
- * 2.
- * E + E/(E+1)
- * 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x)
- * 2
- *
- * 22 <= x <= lnovft : sinh(x) := exp(x)/2
- * lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2)
- * ln2ovft < x : sinh(x) := x*shuge (overflow)
- *
- * Special cases:
- * sinh(x) is |x| if x is +INF, -INF, or NaN.
- * only sinh(0)=0 is exact for finite x.
- */
- #include "math.h"
- #include "math_private.h"
- static const double one = 1.0, shuge = 1.0e307;
- double __ieee754_sinh(double x)
- {
- double t,w,h;
- int32_t ix,jx;
- u_int32_t lx;
- /* High word of |x|. */
- GET_HIGH_WORD(jx,x);
- ix = jx&0x7fffffff;
- /* x is INF or NaN */
- if(ix>=0x7ff00000) return x+x;
- h = 0.5;
- if (jx<0) h = -h;
- /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */
- if (ix < 0x40360000) { /* |x|<22 */
- if (ix<0x3e300000) /* |x|<2**-28 */
- if(shuge+x>one) return x;/* sinh(tiny) = tiny with inexact */
- t = expm1(fabs(x));
- if(ix<0x3ff00000) return h*(2.0*t-t*t/(t+one));
- return h*(t+t/(t+one));
- }
- /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */
- if (ix < 0x40862E42) return h*__ieee754_exp(fabs(x));
- /* |x| in [log(maxdouble), overflowthresold] */
- GET_LOW_WORD(lx,x);
- if (ix<0x408633CE || ((ix==0x408633ce)&&(lx<=(u_int32_t)0x8fb9f87d))) {
- w = __ieee754_exp(0.5*fabs(x));
- t = h*w;
- return t*w;
- }
- /* |x| > overflowthresold, sinh(x) overflow */
- return x*shuge;
- }
- strong_alias(__ieee754_sinh, sinh)
- libm_hidden_def(sinh)
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