public double cosh(double x) {
double ex, mex;
ex = Math.exp(x);
mex = 1 / ex;
return (ex + mex) / 2;
}
public double tanh(double x) {
double ex, mex;
ex = Math.exp(x);
mex = 1 / ex;
return (ex - mex) / (ex + mex);
}