// test_deriv2D.java

class test_deriv2D
{
  test_deriv2D()
  {
    int nx = 20;
    int ny = 18;
    double x[] = new double[nx];
    double y[] = new double[ny];
    double U[][] = new double[nx][ny];
    double D[][] = new double[nx][ny];
    int npx = 8;
    int npy = 9;
    int orderx;
    int ordery;
    double xmin = -1.0;
    double xmax = +1.0;
    double ymin = -0.9;
    double ymax = +0.9;
    double hx, hy;
    double err, maxerr=0.0;
    boolean debug = false;

    System.out.println("test_deriv2D running");
    System.out.println("nx="+nx+", npx="+npx+", xmin="+xmin+", xmax="+xmax);
    System.out.println("ny="+ny+", npy="+npy+", ymin="+ymin+", ymax="+ymax);

    hx = (xmax-xmin)/(double)(nx-1);
    hy = (ymax-ymin)/(double)(ny-1);
    for(int i=0; i<nx; i++)
    {
      x[i] = xmin+hx*i;
      if(debug) System.out.println("i="+i+", x="+x[i]);
      for(int ii=0; ii<ny; ii++)
      {
        y[ii] = ymin+hy*ii;
        U[i][ii] = Math.sin(x[i]+y[ii]);
        if(debug) System.out.println("ii="+ii+",y="+y[ii]+", U="+U[i][ii]); 
      } // ii
    } // i

    orderx = 1;
    ordery = 0;
    System.out.println("orderx="+orderx+", ordery="+ordery);
    new deriv2D(orderx, ordery, npx, nx, x, npy, ny, y, U, D);
    for(int i=0; i<nx; i++)
    {
      for(int ii=0; ii<ny; ii++)
      {
	err = D[i][ii]-Math.cos(x[i]+y[ii]);
        maxerr = Math.max(maxerr, Math.abs(err));
        if(debug) System.out.println("i="+i+", ii="+ii+", U="+U[i][ii]+
                                     ", D="+D[i][ii]+", err="+err);
      } // ii
    } // i
    System.out.println("Ux max error="+maxerr);

    orderx = 0;
    ordery = 1;
    System.out.println("orderx="+orderx+", ordery="+ordery);
    new deriv2D(orderx, ordery, npx, nx, x, npy, ny, y, U, D);
    for(int i=0; i<nx; i++)
    {
      for(int ii=0; ii<ny; ii++)
      {
	err = D[i][ii]-Math.cos(x[i]+y[ii]);
        maxerr = Math.max(maxerr, Math.abs(err));
        if(debug) System.out.println("i="+i+", ii="+ii+", U="+U[i][ii]+
                                     ", D="+D[i][ii]+", err="+err);
      } // ii
    } // i
    System.out.println("Ux max error="+maxerr);

    orderx = 2;
    ordery = 0;
    System.out.println("orderx="+orderx+", ordery="+ordery);
    new deriv2D(orderx, ordery, npx, nx, x, npy, ny, y, U, D);
    for(int i=0; i<nx; i++)
    {
      for(int ii=0; ii<ny; ii++)
      {
	err = D[i][ii]-(-Math.sin(x[i]+y[ii]));
        maxerr = Math.max(maxerr, Math.abs(err));
        if(debug) System.out.println("i="+i+", ii="+ii+", U="+U[i][ii]+
                                     ", D="+D[i][ii]+", err="+err);
      } // ii
    } // i
    System.out.println("Uxx max error="+maxerr);

    orderx = 3;
    ordery = 0; 
    System.out.println("orderx="+orderx+", ordery="+ordery);
    new deriv2D(orderx, ordery, npx, nx, x, npy, ny, y, U, D);
    for(int i=0; i<nx; i++)
    {
      for(int ii=0; ii<ny; ii++)
      {
	err = D[i][ii]-(-Math.cos(x[i]+y[ii]));
        maxerr = Math.max(maxerr, Math.abs(err));
        if(debug) System.out.println("i="+i+", ii="+ii+", U="+U[i][ii]+
                                     ", D="+D[i][ii]+", err="+err);
      } // ii
    } // i
    System.out.println("Uxxx max error="+maxerr);

    orderx = 4;
    ordery = 0;
    System.out.println("orderx="+orderx+", ordery="+ordery);
    new deriv2D(orderx, ordery, npx, nx, x, npy, ny, y, U, D);
    for(int i=0; i<nx; i++)
    {
      for(int ii=0; ii<ny; ii++)
      {
	err = D[i][ii]-Math.sin(x[i]+y[ii]);
        maxerr = Math.max(maxerr, Math.abs(err));
        if(debug) System.out.println("i="+i+", ii="+ii+", U="+U[i][ii]+
                                     ", D="+D[i][ii]+", err="+err);
      } // ii
    } // i
    System.out.println("Uxxxx max error="+maxerr);

    System.out.println("test_deriv2D finished");
  } // end test_deriv2D

  public static void main (String[] args)
  {
    new test_deriv2D();
  }
} // end class test_deriv2D