void r4_fehl ( void f ( float t, float y[], float yp[] ), int neqn, 
  float y[], float t, float h, float yp[], float f1[], float f2[], float f3[], 
  float f4[], float f5[], float s[] );
int r4_rkf45 ( void f ( float t, float y[], float yp[] ), int neqn, 
  float y[], float yp[], float *t, float tout, float *relerr, float abserr, 
  int flag );
float r4_sign ( float x );

void r8_fehl ( void f ( double t, double y[], double yp[] ), int neqn, 
  double y[], double t, double h, double yp[], double f1[], double f2[], double f3[], 
  double f4[], double f5[], double s[] );
int r8_rkf45 ( void f ( double t, double y[], double yp[] ), int neqn, 
  double y[], double yp[], double *t, double tout, double *relerr, double abserr, 
  int flag );
double r8_sign ( double x );

void timestamp ( );