ref: 75d6267a5f788162d92e7a5ae126cd8b0770aa8a
dir: /sys/src/libc/port/sinh.c/
#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; }