/* nag_2d_spline_interpolant (e01dac) Example Program.
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 *
 * Mark 6 revised, 2000.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nage01.h>
#include <nage02.h>

#define F(I, J)  f[my*(I)+(J)]
#define FG(I, J) fg[npy*(I)+(J)]
#define C(I, J)  spline.c[my*(I)+(J)]
int main(int argc, char *argv[])
{
  FILE         *fpin, *fpout;
  Integer      exit_status = 0, i, j, mx, my, npx, npy;
  NagError     fail;
  Nag_2dSpline spline;
  double       *f = 0, *fg = 0, step, *tx = 0, *ty = 0, *x = 0, xhi, xlo;
  double       *y = 0, yhi, ylo;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);

  /* Initialise spline */
  spline.lamda = 0;
  spline.mu = 0;
  spline.c = 0;

  fprintf(fpout,
          "nag_2d_spline_interpolant (e01dac) Example Program Results\n");
  fscanf(fpin, "%*[^\n]"); /* Skip heading in data file */
  /* Read the number of x points, mx, and the values of the
   * x co-ordinates.
   */
  fscanf(fpin, "%ld%ld", &mx, &my);
  if (mx >= 4 && my >= 4)
    {
      if (!(f = NAG_ALLOC(mx*my, double)) ||
          !(x = NAG_ALLOC(mx, double)) ||
          !(y = NAG_ALLOC(my, double)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      fprintf(fpout, "Invalid mx or my.\n");
      exit_status = 1;
      return exit_status;
    }
  for (i = 0; i < mx;  i++)
    fscanf(fpin, "%lf", &x[i]);
  /* Read the number of y points, my, and the values of the
   * y co-ordinates.
   */
  for (i = 0; i < my; i++)
    fscanf(fpin, "%lf", &y[i]);
  /* Read the function values at the grid points. */
  for (j = 0; j < my; j++)
    for (i = 0; i < mx; i++)
      fscanf(fpin, "%lf", &F(i, j));
  /* Generate the (x,y,f) interpolating bicubic B-spline. */
  /* nag_2d_spline_interpolant (e01dac).
   * Interpolating function, bicubic spline interpolant, two
   * variables
   */
  nag_2d_spline_interpolant(mx, my, x, y, f, &spline, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_2d_spline_interpolant (e01dac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print the knot sets, lamda and mu. */
  fprintf(fpout, "Distinct knots in x direction located  at\n");
  for (j = 3; j < spline.nx-3; j++)
    fprintf(fpout, "%12.4f%s", spline.lamda[j],
            ((j-3)%5 == 4 || j == spline.nx-4)?"\n":" ");
  fprintf(fpout, "\nDistinct knots in y direction located  at\n");
  for (j = 3; j < spline.ny-3; j++)
    fprintf(fpout, "%12.4f%s", spline.mu[j],
            ((j-3)%5 == 4 || j == spline.ny-4)?"\n":" ");
  /* Print the spline coefficients. */
  fprintf(fpout, "\nThe B-Spline coefficients:\n");
  for (i = 0; i < mx; i++)
    {
      for (j = 0; j < my; j++)
        fprintf(fpout, "%9.4f", C(i, j));
      fprintf(fpout, "\n");
    }

  /* Evaluate the spline on a regular rectangular grid at npx*npy
   * points over the domain (xlo to xhi) x (ylo to yhi).
   */
  fscanf(fpin, "%ld%lf%lf", &npx, &xlo, &xhi);
  fscanf(fpin, "%ld%lf%lf", &npy, &ylo, &yhi);
  if (npx >= 1 && npy >= 1)
    {
      if (!(fg = NAG_ALLOC(npx*npy, double)) ||
          !(tx = NAG_ALLOC(npx, double)) ||
          !(ty = NAG_ALLOC(npy, double)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      fprintf(fpout, "Invalid npx or npy.\n");
      exit_status = 1;
      return exit_status;
    }
  step = (xhi-xlo)/(double)(npx-1);
  fprintf(fpout, "\nSpline evaluated on a regular mesh "
          "     (x across, y down): \n     ");
  /* Generate nx equispaced x co-ordinates. */
  for (i = 0; i < npx; i++)
    {
      tx[i] = MIN(xlo+i*step, xhi);
      fprintf(fpout, "   %5.2f ", tx[i]);
    }
  step = (yhi-ylo)/(npy-1);
  for (i = 0; i < npy; i++)
    ty[i] = MIN(ylo+i*step, yhi);

  /* Evaluate the spline. */
  /* nag_2d_spline_eval_rect (e02dfc).
   * Evaluation of bicubic spline, at a mesh of points
   */
  nag_2d_spline_eval_rect(npx, npy, tx, ty, fg, &spline, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_2d_spline_eval_rect (e02dfc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print the results. */
  fprintf(fpout, "\n");
  for (j = 0; j < npy; j++)
    {
      fprintf(fpout, "%5.2f", ty[j]);
      for (i = 0; i < npx; i++)
        fprintf(fpout, "%8.3f ", FG(i, j));
      fprintf(fpout, "\n");
    }
  /* Free memory allocated by nag_2d_spline_interpolant (e01dac) */
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  NAG_FREE(spline.lamda);
  NAG_FREE(spline.mu);
  NAG_FREE(spline.c);
  if (f) NAG_FREE(f);
  if (x) NAG_FREE(x);
  if (y) NAG_FREE(y);
  if (fg) NAG_FREE(fg);
  if (tx) NAG_FREE(tx);
  if (ty) NAG_FREE(ty);
  return exit_status;
}