double f(double c_p, double c_n, double t, double s) {
double r690 = 1.0;
double r691 = s;
double r692 = -r691;
double r693 = exp(r692);
double r694 = r690 + r693;
double r695 = r690 / r694;
double r696 = c_p;
double r697 = pow(r695, r696);
double r698 = r690 - r695;
double r699 = c_n;
double r700 = pow(r698, r699);
double r701 = r697 * r700;
double r702 = t;
double r703 = -r702;
double r704 = exp(r703);
double r705 = r690 + r704;
double r706 = r690 / r705;
double r707 = pow(r706, r696);
double r708 = r690 - r706;
double r709 = pow(r708, r699);
double r710 = r707 * r709;
double r711 = r701 / r710;
return r711;
}