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1.1 ! root 1: /* ! 2: * "@(#)sinh.c 1.1" ! 3: */ ! 4: ! 5: /* ! 6: sinh(arg) returns the hyperbolic sine of its floating- ! 7: point argument. ! 8: ! 9: The exponential function is called for arguments ! 10: greater in magnitude than 0.5. ! 11: ! 12: A series is used for arguments smaller in magnitude than 0.5. ! 13: The coefficients are #2029 from Hart & Cheney. (20.36D) ! 14: ! 15: cosh(arg) is computed from the exponential function for ! 16: all arguments. ! 17: */ ! 18: ! 19: double exp(); ! 20: ! 21: static double p0 = -0.6307673640497716991184787251e+6; ! 22: static double p1 = -0.8991272022039509355398013511e+5; ! 23: static double p2 = -0.2894211355989563807284660366e+4; ! 24: static double p3 = -0.2630563213397497062819489e+2; ! 25: static double q0 = -0.6307673640497716991212077277e+6; ! 26: static double q1 = 0.1521517378790019070696485176e+5; ! 27: static double q2 = -0.173678953558233699533450911e+3; ! 28: ! 29: double ! 30: sinh(arg) ! 31: double arg; ! 32: { ! 33: double temp, argsq; ! 34: register sign; ! 35: ! 36: sign = 1; ! 37: if(arg < 0) { ! 38: arg = - arg; ! 39: sign = -1; ! 40: } ! 41: ! 42: if(arg > 21.) { ! 43: temp = exp(arg)/2; ! 44: if (sign>0) ! 45: return(temp); ! 46: else ! 47: return(-temp); ! 48: } ! 49: ! 50: if(arg > 0.5) { ! 51: return(sign*(exp(arg) - exp(-arg))/2); ! 52: } ! 53: ! 54: argsq = arg*arg; ! 55: temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; ! 56: temp /= (((argsq+q2)*argsq+q1)*argsq+q0); ! 57: return(sign*temp); ! 58: } ! 59: ! 60: double ! 61: cosh(arg) ! 62: double arg; ! 63: { ! 64: if(arg < 0) ! 65: arg = - arg; ! 66: if(arg > 21.) { ! 67: return(exp(arg)/2); ! 68: } ! 69: ! 70: return((exp(arg) + exp(-arg))/2); ! 71: }
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