void init_mass_FDF (double X, void * sim_params, double * f, double * df) {
Strategy * p = ( Strategy * ) sim_params;
*f = p->TotalMass(X) - p->offspring_mass();
*df = p->dTotalMass_dm(X) * 1.0;
}
/*functions used to solve initial leaf mass for a given seed size. F gives difference b/w total mass
estimated from leaf mass and seed size. dF gives derivative of F, and FDF gives both */
double init_mass_F(double X, void *sim_params) {
Strategy * p = ( Strategy * ) sim_params;
return p->TotalMass(X) - p->offspring_mass();
}