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