/* 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 <nagf16.h>
#include <nagx04.h>

int main(void)
{
  /* Scalars */
  Integer       i, n, pdvt, pdu;
  Integer       exit_status = 0, ncc = 0, ldc = 1;
  double        zero = 0.0, one = 1.0;
  /* Arrays */
  char          nag_enum_arg[40];
  double        c[1];
  double        *d = 0, *e = 0, *u = 0, *vt = 0;

  /* Nag Types */
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;

  INIT_FAIL(fail);

  printf("nag_dbdsqr (f08mec) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%ld%*[^\n]", &n);
  if (n < 0)
    {
      printf("Invalid n\n");
      exit_status = 1;
      goto END;;
    }

#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;
#else
#define U(I, J)  u[(I-1)*pdu + J - 1]
#define VT(I, J) vt[(I-1)*pdvt + J - 1]
  order = Nag_RowMajor;
#endif
  pdu = n;
  pdvt = n;

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

  /* Read B from data file */
  for (i = 0; i < n; ++i)  scanf("%lf", &d[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n - 1; ++i) scanf("%lf", &e[i]);
  scanf("%*[^\n]");

  scanf("%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 to obtain SVD of input
   * bidiagonal matrix nag_dge_load (f16qhc).
   * General matrix initialisation.
   */
  nag_dge_load(order, n, n, zero, one, u, pdu, &fail);
  nag_dge_load(order, n, n, zero, one, vt, pdvt, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dge_load (f16qhc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* nag_dbdsqr (f08mec).
   * SVD of real bidiagonal matrix reduced from real general
   * matrix.
   */
  nag_dbdsqr(order, uplo, n, n, n, ncc, d, e, vt, pdvt, u, pdu, c, ldc, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dbdsqr (f08mec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print singular values, left & right singular vectors */
  printf("\nSingular values\n   ");
  for (i = 0; i < n; ++i) printf(" %7.4f%s", d[i], i%8 == 7?"\n":"");
  printf("\n\n");

  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         vt, pdvt, "Right singular vectors, by row", 0,
                         &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  printf("\n");
  /* nag_gen_real_mat_print (x04cac), see above. */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n,
                         u, pdu, "Left singular vectors, by column", 0,
                         &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);
  if (u) NAG_FREE(u);
  if (vt) NAG_FREE(vt);

  return exit_status;
}