void spline_print(FILE *fp, spline *s)
{
  int        i;
  fprintf(fp,"Spline: ");
  if ( s == NULL )
  {
    fprintf(fp,"NULL\n");
    return;
  }
  fprintf(fp,"length: %d\n", s->length);
  fprintf(fp,"xlist: ");
  for ( i = 0; i < s->length; i++ )
    fprintf(fp,"%20.14g ", s->xlist[i]);
  fprintf(fp,"\n");
  fprintf(fp,"ylist: ");
  for ( i = 0; i < s->length; i++ )
    fprintf(fp,"%20.14g ", s->ylist[i]);
  fprintf(fp,"\n");
  fprintf(fp,"Mlist: ");
  for ( i = 0; i < s->length; i++ )
    fprintf(fp,"%20.14g ", s->Mlist[i]);
  fprintf(fp,"\n");
}