double jacobi_cn ( double u, double m );
double jacobi_dn ( double u, double m );
double jacobi_sn ( double u, double m );
void sncndn ( double u, double m, double *sn, double *cn, double *dn );
void jacobi_cn_values ( int *n_data, double *u, double *a, double *k, 
  double *m, double *fx );
void jacobi_dn_values ( int *n_data, double *u, double *a, double *k, 
  double *m, double *fx );
void jacobi_sn_values ( int *n_data, double *u, double *a, double *k, 
  double *m, double *fx );