/* nag_bessel_k_alpha (s18egc) Example Program.
 *
 * Copyright 2000 Numerical Algorithms Group.
 *
 * NAG C Library
 *
 * Mark 6, 2000.
 * Mark 8 revised, 2004.
 */

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nags.h>

int main(int argc, char *argv[])
{
  FILE     *fpin, *fpout;
  Integer  exit_status = 0, i, ia, ja, nl;
  NagError fail;
  double   alpha, *b = 0, x;

  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);

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n]");
  fprintf(fpout, "nag_bessel_k_alpha (s18egc) Example Program Results\n");
  if (!(b = NAG_ALLOC(101, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  while (fscanf(fpin, "%lf %ld %ld %ld%*[^\n]", &x, &ia, &ja,
                &nl) != EOF)
    {
      fprintf(fpout, "  x      ia     ja     nl\n");
      fprintf(fpout, "%4.1f %6ld %6ld %6ld\n\n", x, ia, ja,
              nl);
      /* nag_bessel_k_alpha (s18egc).
       * Modified Bessel functions K_(alpha~+~n)(x) for real
       * x~>~0, selected values of alpha~>=~0 and
       * n~=~0~,~1~,~...~,~N
       */
      nag_bessel_k_alpha(x, ia, ja, nl, b, &fail);
      if (fail.code != NE_NOERROR)
        {
          fprintf(fpout, "Error from nag_bessel_k_alpha (s18egc).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }
      fprintf(fpout, " Requested values of K_alpha(x)\n\n");
      alpha = (double) ia / (double) ja;
      fprintf(fpout, "     alpha        K_alpha(x)\n");
      for (i = 0; i <= nl; ++i)
        {
          fprintf(fpout, " %13.4e %13.4e\n", alpha, b[i]);
          alpha += 1.0;
        }
    }

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (b) NAG_FREE(b);
  return exit_status;
}