ref: 8d51e7fa1a1dbcbde513c2b756d504c879598907
dir: /sys/src/ape/lib/ap/math/sinh.c/
/* 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. */ #include <math.h> #include <errno.h> 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 = 1; if(arg < 0) { arg = - arg; sign = -1; } if(arg > 21) { if(arg >= HUGE_VAL){ errno = ERANGE; temp = HUGE_VAL; } else temp = exp(arg)/2; if(sign > 0) return temp; else return -temp; } if(arg > 0.5) return sign*(exp(arg) - exp(-arg))/2; argsq = arg*arg; temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; temp /= (((argsq+q2)*argsq+q1)*argsq+q0); return sign*temp; } double cosh(double arg) { if(arg < 0) arg = - arg; if(arg > 21) { if(arg >= HUGE_VAL){ errno = ERANGE; return HUGE_VAL; } else return(exp(arg)/2); } return (exp(arg) + exp(-arg))/2; }