/* ---------------------------------- */
/* save as fa.h                   */
/* ---------------------------------- */
double M(
double x,
double y,
double z)
{
      return( (3*x) );
}
char  Meq[] = "+ 3*x";
/* ---------------------------------- */
double N(
double x,
double y,
double z)
{
      return( (3*y) );
}
char  Neq[] = "+ 3*y";
/* ---------------------------------- */
double P(
double x,
double y,
double z)
{
      return( (z) );
}
char  Peq[] = " + z";
/* ---------------------------------- */
double f(
double x,
double y)
{
      return( (9-x*x-y*y) );
}
char  feq[] = "9-x**2-y**2";
/* ---------------------------------- */
double u(
double y)
{
 return(       -sqrt(9-y*y) );
}
char  ueq[] = "-sqrt(9-y**2)";
/* ---------------------------------- */
double v(
double y)
{
 return(       sqrt(9-y*y)  );
}
char  veq[] = "+sqrt(9-y**2)";
/* ---------------------------------- */
/* ---------------------------------- */