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Mathc initiation/a460

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x_jdudv.h
/* ---------------------------------- */
/* save as x_jdudv.h                  */
/* ---------------------------------- */
double J_du(
double (*P_f)(double x, double y),

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

double (*P_ax)(double y),
double (*P_bx)(double y),
   int     nx,
   
double y
)
{
double x = 0;
   int i = 0;
double m = 0.;
double M = 0.;

pt2d   p;

 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 = ((*P_ax)(y)) + i*(((*P_bx)(y))-((*P_ax)(y)))/nx;

  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_bx)(y)) -((*P_ax)(y)))*M) / (3*nx) );
}
/* ---------------------------------- */
double J_dudv(
double (*P_f)(double x, double y),

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

double (*P_ax)(double y),
double (*P_bx)(double y),
   int     nx,
   
double ay,
double by,
   int ny
)
{
   int i = 0;
double m = 0.;
double M = 0.;

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

  M += m *   J_du((*P_f),
                  (*P_u),(*P_v),
                  (*P_ax),(*P_bx),nx, 
                  (ay+i*(by-ay)/ny));
 }

  return( ((by-ay)*M) / (3*ny) );
}
/* ---------------------------------- */
/* ---------------------------------- */


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