/* nag_real_cholesky_solve_mult_rhs (f04agc) Example Program.
 *
 * Copyright 1996 Numerical Algorithms Group.
 *
 * Mark 4, 1996.
 * Mark 8 revised, 2004.
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagf03.h>
#include <nagf04.h>

#define A(I,J) a[(I)*tda + J]
#define B(I,J) b[(I)*tdb + J]
#define X(I,J) x[(I)*tdx + J]

int main(void)
{
  Integer exit_status=0, i, id, j, n, nrhs, tda, tdb, tdx;
  NagError fail;
  double *a=0, *b=0, d1, *p=0, *x=0;

  INIT_FAIL(fail);
  Vprintf("nag_real_cholesky_solve_mult_rhs (f04agc) Example Program"
          " Results\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n]");
  Vscanf("%ld", &n);
  nrhs = 1;
  if (n>=1)
    {
      if ( !( a = NAG_ALLOC(n*n, double)) ||
           !( b = NAG_ALLOC(n*nrhs, double)) ||
           !( p = NAG_ALLOC(n, double)) ||
           !( x = NAG_ALLOC(n*nrhs, double)) )
        {
          Vprintf("Allocation failure\n");
          exit_status = -1;
          goto END;
        }
      tda = n;
      tdb = nrhs;
      tdx = nrhs;
    }
  else
    {
      Vprintf("Invalid n.\n");
      exit_status = 1;
      return exit_status;
    }
  for (i=0; i<n; ++i)
    for (j=0; j<n; ++j)
      Vscanf("%lf", &A(i,j));
  for (i=0; i<n; ++i)
    for (j=0; j<nrhs; ++j)
      Vscanf("%lf", &B(i,j));

  /* Cholesky decomposition */
  /* nag_real_cholesky (f03aec).
   * LL^T factorization and determinant of real symmetric
   * positive-definite matrix
   */
  nag_real_cholesky(n, a, tda, p, &d1, &id, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_real_cholesky (f03aec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Approximate solution of linear equations */
  /* nag_real_cholesky_solve_mult_rhs (f04agc).
   * Approximate solution of real symmetric positive-definite
   * simultaneous linear equations (coefficient matrix already
   * factorized by nag_real_cholesky (f03aec))
   */
  nag_real_cholesky_solve_mult_rhs(n, nrhs, a, tda, p, b, tdb, x, tdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_real_cholesky_solve_mult_rhs (f04agc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  Vprintf("\n Solution\n");
  for (i=0; i<n; ++i)
    {
      for (j=0; j<nrhs; ++j)
        Vprintf("%9.4f", X(i,j));
      Vprintf("\n");
    }
 END:
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (p) NAG_FREE(p);
  if (x) NAG_FREE(x);
  return exit_status;
}