double filon_fun_cos ( int n, double *f ( int n, double x[] ), double a, 
  double b, double t );
double filon_tab_cos ( int n, double ftab[], double a, double b, double t );
double filon_fun_sin ( int n, double *f ( int n, double x[] ), double a, 
  double b, double t );
double filon_tab_sin ( int n, double ftab[], double a, double b, double t );
int i4_power ( int i, int j );
void timestamp ( );