/* ---------------------------------- */
/* save as fb.h                       */
/* --------------------------------- */
double M(
double x,
double y,
double z)
{
      return(   (2*y) );
}
char  Meq[] = "+ 2*y";
/* --------------------------------- */
double N(
double x,
double y,
double z)
{
      return(   (exp(z)) );
}
char  Neq[] = "+ exp(z)";
/* --------------------------------- */
double P(
double x,
double y,
double z)
{
      return(    -(atan(x)) );
}
char  Peq[] = " - atan(x)";
/* --------------------------------- */
/* --------------------------------- */
double f(
double x,
double y)
{
      return( (4-x*x-y*y) );
}
char  feq[] = "4-x**2-y**2";
/* --------------------------------- */
/* --------------------------------- */
double u(
double y)
{
 return(       -sqrt(4-y*y) );
}
char  ueq[] = "-sqrt(4-y**2)";
/* --------------------------------- */
double v(
double y)
{
 return(       sqrt(4-y*y)  );
}
char  veq[] = "+sqrt(4-y**2)";
/* --------------------------------- */
/* --------------------------------- */
double g(
double t)
{
        return( 2*cos(t));
}
char  geq[] =  " 2*cos(t)";
/* --------------------------------- */
double h(
double t)
{
        return( 2*sin(t));
}
char  heq[] =  " 2*sin(t)";
/* --------------------------------- */
double k(
double t)
{
        return( 0);
}
char  keq[] =  "0";
/* --------------------------------- */
/* --------------------------------- */