Mathc initiation/a461

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x_jdvdu.h
/* ---------------------------------- */
/* save as x_jdvdu.h                  */
/* ---------------------------------- */
double J_dv(
double (*P_f)(double x, double y),

double (*P_u)(double s, double t),
double (*P_v)(double s, double t),

double (*P_ay)(double x),
double (*P_by)(double x),
   int     ny,
   
double x
)
{
double y = 0;

   int i = 0;
double m = 0.;
double M = 0.;

pt2d   p;

 for(i = 0; i <= ny; i++)
 {
       if(i ==0 || i== ny){m = 1.;}
  else if(fmod(i,2) == 0) {m = 2.;}
  else                    {m = 4.;}
  
  y = ((*P_ay)(x)) + i*(((*P_by)(x))-((*P_ay)(x)))/ny;

  p.x = x;
  p.y = y;  
    
  M += m * (*P_f)((*P_u)(x,y), (*P_v)(x,y))
                             *   
      fabs(fxy_x((*P_u),H,p) * fxy_y((*P_v),H,p)
                             -
           fxy_x((*P_v),H,p) * fxy_y((*P_u),H,p));
 }

  return( ((((*P_by)(x)) -((*P_ay)(x)))*M) / (3*ny) );
}
/* ---------------------------------- */
double J_dvdu(
double (*P_f)(double x, double y),

double (*P_u)(double s, double t),
double (*P_v)(double s, double t),

double (*P_ay)(double x),
double (*P_by)(double x),
   int     ny,

double ax,
double bx,
   int nx
)
{
double x = 0;

   int i = 0;
double m = 0.;
double M = 0.;

 for(i = 0; i <= nx; i++)
 {
       if(i ==0 || i== nx){m = 1.;}
  else if(fmod(i,2) == 0) {m = 2.;}
  else                    {m = 4.;}

  x = (ax + i*(bx-ax)/nx);
  
  M += m *   J_dv((*P_f),  
                  (*P_u), (*P_v),
                  (*P_ay),(*P_by),ny, x);
 }

  return( ((bx -ax)*M) / (3*nx) );
}
/* ---------------------------------- */
/* ---------------------------------- */


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