tanh function
Hyperbolic Tangent in radian.
Implementation
double tanh(double angle) {
if (angle > 19.1) {
return 1.0;
}
if (angle < -19.1) {
return -1.0;
}
var e1 = stdmath.exp(angle);
var e2 = stdmath.exp(-angle);
return (e1 - e2) / (e1 + e2);
}