72 lines
1.4 KiB
C
72 lines
1.4 KiB
C
/*
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sinh(arg) returns the hyperbolic sine of its floating-
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point argument.
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The exponential function is called for arguments
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greater in magnitude than 0.5.
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A series is used for arguments smaller in magnitude than 0.5.
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The coefficients are #2029 from Hart & Cheney. (20.36D)
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cosh(arg) is computed from the exponential function for
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all arguments.
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*/
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#include <math.h>
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#include <errno.h>
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static double p0 = -0.6307673640497716991184787251e+6;
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static double p1 = -0.8991272022039509355398013511e+5;
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static double p2 = -0.2894211355989563807284660366e+4;
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static double p3 = -0.2630563213397497062819489e+2;
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static double q0 = -0.6307673640497716991212077277e+6;
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static double q1 = 0.1521517378790019070696485176e+5;
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static double q2 = -0.173678953558233699533450911e+3;
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double
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sinh(double arg)
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{
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double temp, argsq;
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int sign;
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sign = 1;
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if(arg < 0) {
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arg = - arg;
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sign = -1;
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}
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if(arg > 21) {
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if(arg >= HUGE_VAL){
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errno = ERANGE;
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temp = HUGE_VAL;
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} else
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temp = exp(arg)/2;
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if(sign > 0)
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return temp;
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else
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return -temp;
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}
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if(arg > 0.5)
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return sign*(exp(arg) - exp(-arg))/2;
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argsq = arg*arg;
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temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg;
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temp /= (((argsq+q2)*argsq+q1)*argsq+q0);
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return sign*temp;
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}
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double
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cosh(double arg)
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{
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if(arg < 0)
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arg = - arg;
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if(arg > 21) {
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if(arg >= HUGE_VAL){
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errno = ERANGE;
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return HUGE_VAL;
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} else
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return(exp(arg)/2);
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}
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return (exp(arg) + exp(-arg))/2;
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}
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