/* nag_herm_posdef_tridiag_lin_solve (f04cgc) Example Program.
 *
 * Copyright 2004 Numerical Algorithms Group.
 *
 * Mark 8, 2004.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf04.h>
#include <nagx04.h>

int main(void)
{

  /* Scalars */
  double errbnd, rcond;
  Integer exit_status, i,  j, n, nrhs, pdb;

  /* Arrays */
  char *clabs=0, *rlabs=0;
  Complex *b=0, *e=0;
  double *d__=0;

  /* Nag types */
  NagError fail;
  Nag_OrderType order;

#ifdef NAG_COLUMN_MAJOR
#define B(I,J) b[(J-1)*pdb + I - 1]
  order = Nag_ColMajor;
#else
#define B(I,J) b[(I-1)*pdb + J - 1]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  INIT_FAIL(fail);

  Vprintf("nag_herm_posdef_tridiag_lin_solve (f04cgc) Example Program"
          " Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%ld%*[^\n] ",   &n,  &nrhs);
  if (n>0 && nrhs>0)
    {
      /* Allocate memory */
      if ( !(clabs = NAG_ALLOC(2, char)) ||
           !(rlabs = NAG_ALLOC(2, char)) ||
           !(b = NAG_ALLOC(n*nrhs, Complex)) ||
           !(e = NAG_ALLOC(n-1, Complex)) ||
           !(d__ = NAG_ALLOC(n, double)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
#ifdef NAG_COLUMN_MAJOR
      pdb = n;
#else
      pdb = nrhs;
#endif
    }
  else
    {
      Vprintf("%s\n",   "n and/or nrhs too small");
      exit_status = 1;
      return exit_status;
    }

  /* Read A from data file */
  for (i = 1; i <= n; ++i)
    {
      Vscanf("%lf", &d__[i - 1]);
    }
  Vscanf("%*[^\n] ");
  for (i = 1; i <= n - 1; ++i)
    {
      Vscanf(" ( %lf , %lf )", &e[i - 1].re, &e[i - 1].im);
    }
  Vscanf("%*[^\n] ");

  /* Read B from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        {
          Vscanf(" ( %lf , %lf )", &B(i,j).re, &B(i,j).im);
        }
    }
  Vscanf("%*[^\n] ");

  /* Solve the equations AX = B for X */
  /* nag_herm_posdef_tridiag_lin_solve (f04cgc).
   * Computes the solution and error-bound to a complex
   * Hermitian positive-definite tridiagonal system of linear
   * equations
   */
  nag_herm_posdef_tridiag_lin_solve(order, n, nrhs, d__, e, b, pdb, &rcond,
                                    &errbnd, &fail);
  if (fail.code == NE_NOERROR)
    {

      /* Print solution, estimate of condition number and approximate */
      /* error bound */
      /* nag_gen_complx_mat_print_comp (x04dbc).
       * Print complex general matrix (comprehensive)
       */
      nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag,
                                    n, nrhs, b, pdb, Nag_BracketForm, 0,
                                    "Solution", Nag_IntegerLabels, 0,
                                    Nag_IntegerLabels, 0, 80, 0, 0, &fail);
      if (fail.code != NE_NOERROR)
        {
          Vprintf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }

      Vprintf("\n");
      Vprintf("%s\n%8s%9.1e\n", "Estimate of condition number", "", 1.0/rcond);
      Vprintf("\n\n");
      Vprintf("%s\n%8s%9.1e\n\n",
              "Estimate of error bound for computed solutions", "", errbnd);
    }
  if (fail.code == NE_RCOND)
    {
      /* Matrix A is numerically singular.  Print estimate of */
      /* reciprocal of condition number and solution */

      Vprintf("\n");
      Vprintf("%s\n%8s%9.1e\n\n\n",
              "Estimate of reciprocal of condition number", "", rcond);
      /* nag_gen_complx_mat_print_comp (x04dbc), see above. */
      nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag,
                                    n, nrhs, b, pdb, Nag_BracketForm, 0,
                                    "Solution", Nag_IntegerLabels, 0,
                                    Nag_IntegerLabels, 0, 80, 0, 0, &fail);
      if (fail.code != NE_NOERROR)
        {
          Vprintf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }
    }
  if (fail.code == NE_POS_DEF)
    {
      Vprintf("%s%3ld%s\n\n",   "The leading minor of order ",
              fail.errnum,  " is not positive definite");
    }
 END:
  if (clabs) NAG_FREE(clabs);
  if (rlabs) NAG_FREE(rlabs);
  if (b) NAG_FREE(b);
  if (e) NAG_FREE(e);
  if (d__) NAG_FREE(d__);

  return exit_status;
}
#undef B