/* nag_dbdsqr (f08mec) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf08.h>
#include <nagx04.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* Scalars */
  Integer       i, j, n, pdvt, pdu, d_len, e_len;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  double        *c = 0, *d = 0, *e = 0, *u = 0, *vt = 0;

  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);
  (void) nag_example_file_io(argc, argv, "-nag_write", &outfile);
  fprintf(fpout, "nag_dbdsqr (f08mec) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
#define U(I, J)  u[(J-1)*pdu + I - 1]
#define VT(I, J) vt[(J-1)*pdvt + I - 1]
  order = Nag_ColMajor;
  pdu = n;
  pdvt = n;
#else
#define U(I, J)  u[(I-1)*pdu + J - 1]
#define VT(I, J) vt[(I-1)*pdvt + J - 1]
  order = Nag_RowMajor;
  pdu = n;
  pdvt = n;
#endif
  d_len = n;
  e_len = n - 1;

  /* Allocate memory */
  if (!(c = NAG_ALLOC(1 * 1, double)) ||
      !(d = NAG_ALLOC(d_len, double)) ||
      !(e = NAG_ALLOC(e_len, double)) ||
      !(u = NAG_ALLOC(n * n, double)) ||
      !(vt = NAG_ALLOC(n * n, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read B from data file */
  for (i = 1; i <= n; ++i)
    fscanf(fpin, "%lf", &d[i - 1]);
  fscanf(fpin, "%*[^\n] ");
  for (i = 1; i <= n - 1; ++i)
    fscanf(fpin, "%lf", &e[i - 1]);
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);

  /* Initialise U and VT to be the unit matrix */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= n; ++j)
        {
          U(i, j) = 0.0;
          VT(i, j) = 0.0;
        }
      U(i, i) = 1.0;
      VT(i, i) = 1.0;
    }

  /* Calculate the SVD of B */
  /* nag_dbdsqr (f08mec).
   * SVD of real bidiagonal matrix reduced from real general
   * matrix
   */
  nag_dbdsqr(order, uplo, n, n, n, 0, d, e, vt, pdvt, u, pdu, c,
             1, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dbdsqr (f08mec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print singular values, left & right singular vectors */
  fprintf(fpout, "\nSingular values\n");
  for (i = 1; i <= n; ++i)
    fprintf(fpout, "%8.4f%s", d[i-1], i%8 == 0?"\n":" ");
  fprintf(fpout, "\n\n");

  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  if (outfile) fclose(fpout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         vt, pdvt, "Right singular vectors, by row", outfile,
                         &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  fprintf(fpout, "\n");
  /* nag_gen_real_mat_print (x04cac), see above. */
  if (outfile) fclose(fpout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         u, pdu, "Left singular vectors, by column", outfile,
                         &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (c) NAG_FREE(c);
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (u) NAG_FREE(u);
  if (vt) NAG_FREE(vt);

  return exit_status;
}