/* nag_sparse_sym_basic_setup (f11gdc) Example Program.
 *
 * Copyright 2011, Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <math.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf11.h>
int main(void)
{
  /* Scalars */
  Integer                 exit_status = 0;
  double                  anorm, dscale, dtol, sigerr, sigmax, sigtol, 
                          stplhs, stprhs, tol;
  Integer                 i, irevcm, iterm, itn, its, la, lfill,
                          lwork, lwreq, maxitn, maxits, monit, n, nnz, 
                          nnzc, npivm;
  /* Arrays */
  char                    nag_enum_arg[100];
  double                  *a = 0, *b = 0, *wgt = 0, *work = 0, *x = 0;
  Integer                 *icol = 0, *ipiv = 0, *irow = 0, *istr = 0;
  /* NAG types */
  Nag_SparseSym_Piv       pstrat;
  Nag_SparseSym_Method    method;
  Nag_SparseSym_PrecType  precon;
  Nag_NormType            norm;
  Nag_SparseSym_Weight    weight;
  Nag_SparseSym_Fact      mic;
  Nag_Sparse_Comm         comm;
  Nag_SparseSym_Bisection sigcmp;
  NagError                fail, fail1;

  INIT_FAIL(fail);
  INIT_FAIL(fail1);

  printf("nag_sparse_sym_basic_setup (f11gdc) Example Program Results\n");

  /* Skip heading in data file*/
  scanf("%*[^\n]");
  scanf("%ld%*[^\n]", &n);
  scanf("%ld%*[^\n]", &nnz);
  la = 2 * nnz;
  lwork = 200;
  if (
      !(a = NAG_ALLOC(la, double)) ||
      !(b = NAG_ALLOC(n, double)) ||
      !(wgt = NAG_ALLOC(n, double)) ||
      !(work = NAG_ALLOC(lwork, double)) ||
      !(x = NAG_ALLOC(n, double)) ||
      !(icol = NAG_ALLOC(la, Integer)) ||
      !(ipiv = NAG_ALLOC(n, Integer)) ||
      !(irow = NAG_ALLOC(la, Integer)) ||
      !(istr = NAG_ALLOC(n + 1, Integer))
    ) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
  /* Read or initialize the parameters for the iterative solver*/
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  scanf("%s%*[^\n]", nag_enum_arg);
  method = (Nag_SparseSym_Method) nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  precon = (Nag_SparseSym_PrecType) nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  sigcmp = (Nag_SparseSym_Bisection)  nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  norm = (Nag_NormType) nag_enum_name_to_value(nag_enum_arg);

  scanf("%s%*[^\n]", nag_enum_arg);
  weight = (Nag_SparseSym_Weight) nag_enum_name_to_value(nag_enum_arg);

  scanf("%ld%*[^\n]", &iterm);
  scanf("%lf%ld%*[^\n]",&tol, &maxitn);
  scanf("%ld%*[^\n] ", &monit);

  /* Read the parameters for the preconditioner*/
  scanf("%ld%lf%*[^\n]", &lfill, &dtol);
  scanf("%s%*[^\n]", nag_enum_arg);
  mic = (Nag_SparseSym_Fact) nag_enum_name_to_value(nag_enum_arg);
  scanf("%lf%*[^\n]", &dscale);
  scanf("%s%*[^\n]", nag_enum_arg);
  pstrat = (Nag_SparseSym_Piv) nag_enum_name_to_value(nag_enum_arg);

  /* Read the non-zero elements of the matrix A*/
  for (i = 0; i < nnz; i++) 
    scanf("%lf%ld%ld%*[^\n]", &a[i], &irow[i], &icol[i]);

  /* Read right-hand side vector b and initial approximate solution x*/
  for (i = 0; i < n; i++) scanf("%lf", &b[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n; i++) scanf("%lf", &x[i]);

  printf("\nSolve a system of linear equations using the ");
  if (method == Nag_SparseSym_CG) 
    printf("conjugate gradient method (CG)\n");
  else if (method == Nag_SparseSym_SYMMLQ)
    printf("Lanczos method (SYMMLQ)\n");
  else if (method == Nag_SparseSym_MINRES)
    printf("minimum residual method (MINRES)\n");

  /* Calculate incomplete Cholesky factorization as preconditioner using
   * nag_sparse_sym_chol_fac (f11jac).
   * Incomplete Cholesky factorization (symmetric)
   */
  nag_sparse_sym_chol_fac(n, nnz, &a, &la, &irow, &icol, lfill, dtol, mic, 
			  dscale, pstrat, ipiv, istr, &nnzc, &npivm, &comm,
			  &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_sparse_sym_chol_fac (f11jac)\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Initialize the solver using nag_sparse_sym_basic_setup (f11gdc).
   * Real sparse symmetric linear systems, setup for f11gec
   */
  anorm = 0.0;
  sigmax = 0.0;
  sigtol = 0.01;
  maxits = n;
  nag_sparse_sym_basic_setup(method, precon, sigcmp, norm, weight, iterm, n,
			     tol, maxitn, anorm, sigmax, sigtol, maxits, 
			     monit, &lwreq, work, lwork, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_sparse_sym_basic_setup (f11gdc)\n%s\n",
	     fail.message);
      exit_status = 2;
      goto END;
    }

  /* Call repeatedly to solve the equations
   * Note that the arrays b and x are overwritten
   * On final exit, x will contain the solution and b the residual vector
   */
  irevcm = 0;
  lwreq = lwork;
  /* First call of nag_sparse_sym_basic_solver (f11gec).
   * Real sparse symmetric linear systems, preconditioned conjugate 
   * gradient or Lanczos
   */
  nag_sparse_sym_basic_solver(&irevcm, x, b, wgt, work, lwreq, &fail);
  while (irevcm != 4) {
    switch (irevcm) {
    case 1:
      /* nag_sparse_sym_matvec (f11xec)
       * Real sparse symmetric matrix vector multiply 
       */
      nag_sparse_sym_matvec(n, nnz, a, irow, icol, Nag_SparseSym_NoCheck, 
			    x, b, &fail1);
      break;
    case 2:
      /* nag_sparse_sym_precon_ichol_solve (f11jbc).
       * Solution of linear system involving incomplete Cholesky 
       * preconditioning matrix generated by f11jac
       */
      nag_sparse_sym_precon_ichol_solve(n, a, la, irow, icol, ipiv, istr, 
					Nag_SparseSym_NoCheck, x, b, &fail1);
      break;
    case 3:
      /* nag_sparse_sym_basic_diagnostic (f11gfc).
       * Real sparse symmetric linear systems, diagnostic for f11gec
       */
      nag_sparse_sym_basic_diagnostic(&itn, &stplhs, &stprhs, &anorm, 
				      &sigmax, &its, &sigerr, work, lwreq,
				      &fail1);
      printf("\nMonitoring at iteration no.%4ld\n", itn);
      printf("residual norm: %14.4e\n", stplhs);
      printf("  Solution vector  Residual vector\n");
      for (i = 0; i < n; i++) printf("%16.4e%16.4e\n", x[i], b[i]);
      printf("\n");
    }
    if (fail1.code != NE_NOERROR) irevcm = 6;
    /* Next call of nag_sparse_sym_basic_solver (f11gec). */
    nag_sparse_sym_basic_solver(&irevcm, x, b, wgt, work, lwreq, &fail);
  }
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_sparse_sym_basic_solver (f11gec).\n%s\n",
	   fail.message);
    exit_status = 3;
    goto END;
  }

  /* Obtain information about the computation using 
   * nag_sparse_sym_basic_diagnostic(f11gfc).
   * Real sparse symmetric linear systems, diagnostic for solver.
   */
  nag_sparse_sym_basic_diagnostic(&itn, &stplhs, &stprhs, &anorm, &sigmax,
				  &its, &sigerr, work, lwreq, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_sparse_sym_basic_diagnostic (f11gfc)\n%s\n",
	     fail.message);
      exit_status = 4;
      goto END;
    }
  /* Print the output data*/
  printf("Final Results\n");
  printf("Number of iterations for convergence:     %5ld \n", itn);
  printf("Residual norm:                            %14.4e\n", stplhs);
  printf("Right-hand side of termination criterion: %14.4e\n", stprhs);
  printf("1-norm of matrix A:                       %14.4e\n", anorm);
  printf("Largest singular value of A_bar:          %14.4e\n\n", sigmax);
  /* Output x*/
  printf("%14s%14s\n","Solution","Residual");
  for (i = 0; i < n; i++) printf("%14.4e%14.4e\n", x[i], b[i]);
  printf("\n");

 END:

  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (wgt) NAG_FREE(wgt);
  if (work) NAG_FREE(work);
  if (x) NAG_FREE(x);
  if (icol) NAG_FREE(icol);
  if (ipiv) NAG_FREE(ipiv);
  if (irow) NAG_FREE(irow);
  if (istr) NAG_FREE(istr);
  return exit_status;
}