ref: 187806ad2021994c4e841d4dbddc569d51023bb0
dir: /sys/src/ape/lib/ap/math/tanh.c/
#include <math.h> /* tanh(arg) computes the hyperbolic tangent of its floating point argument. sinh and cosh are called except for large arguments, which would cause overflow improperly. */ double tanh(double arg) { if(arg < 0) { arg = -arg; if(arg > 21) return -1; return -sinh(arg)/cosh(arg); } if(arg > 21) return 1; return sinh(arg)/cosh(arg); }