/* nag_linsys_complex_posdef_band_solve (f04cfc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.1, 2024.
 */

#include <nag.h>
#include <stdio.h>

int main(void) {
  double errbnd, rcond;
  Integer exit_status, i, j, kd, n, nrhs, pdab, pdb;

  /* Arrays */
  char nag_enum_arg[20];
  char *clabs = 0, *rlabs = 0;
  Complex *ab = 0, *b = 0;

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

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

  exit_status = 0;
  INIT_FAIL(fail);

  printf("nag_linsys_complex_posdef_band_solve (f04cfc)"
         " Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &kd, &nrhs);
  if (n > 0 && kd > 0 && nrhs > 0) {
    /* Allocate memory */
    if (!(clabs = NAG_ALLOC(2, char)) || !(rlabs = NAG_ALLOC(2, char)) ||
        !(ab = NAG_ALLOC((kd + 1) * n, Complex)) ||
        !(b = NAG_ALLOC(n * nrhs, Complex))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
    pdab = kd + 1;
#ifdef NAG_COLUMN_MAJOR
    pdb = n;
#else
    pdb = nrhs;
#endif
  } else {
    printf("%s\n", "One or more of n, kd and nrhs is too small");
    exit_status = 1;
    return exit_status;
  }

  /* Read uplo storage name for the matrix A and convert to value. */
  scanf("%19s%*[^\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);

  /* Read the upper or lower triangular part of the band matrix A */
  /* from data file */

  if (uplo == Nag_Upper) {
    for (i = 1; i <= n; ++i) {
      for (j = i; j <= MIN(n, i + kd); ++j) {
        scanf(" ( %lf , %lf )", &AB_U(i, j).re, &AB_U(i, j).im);
      }
      scanf("%*[^\n] ");
    }
  } else {
    for (i = 1; i <= n; ++i) {
      for (j = MAX(1, i - kd); j <= i; ++j) {
        scanf(" ( %lf , %lf )", &AB_L(i, j).re, &AB_L(i, j).im);
      }
      scanf("%*[^\n] ");
    }
  }

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

  /* Solve the equations AX = B for X */
  /* nag_linsys_complex_posdef_band_solve (f04cfc).
   * Computes the solution and error-bound to a complex
   * Hermitian positive-definite banded system of linear
   * equations
   */
  nag_linsys_complex_posdef_band_solve(order, uplo, n, kd, nrhs, ab, pdab, b,
                                       pdb, &rcond, &errbnd, &fail);

  if (fail.code == NE_NOERROR) {
    /* Print solution, estimate of condition number and approximate *
     * error bound */
    /* nag_file_print_matrix_complex_gen_comp (x04dbc).
     * Print complex general matrix (comprehensive)
     */
    fflush(stdout);
    nag_file_print_matrix_complex_gen_comp(
        order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, pdb,
        Nag_BracketForm, "%7.4f", "Solution", Nag_IntegerLabels, 0,
        Nag_IntegerLabels, 0, 80, 0, 0, &fail);
    if (fail.code != NE_NOERROR) {
      printf(
          "Error from nag_file_print_matrix_complex_gen_comp (x04dbc).\n%s\n",
          fail.message);
      exit_status = 1;
      goto END;
    }

    printf("\n%s\n%4s%10.1e\n\n", "Estimate of condition number", "",
           1.0 / rcond);
    printf("\n%s\n%4s%10.1e\n\n",
           "Estimate of error bound for computed solutions", "", errbnd);
  } else if (fail.code == NE_RCOND) {
    /* Matrix A is numerically singular.  Print estimate of */
    /* reciprocal of condition number and solution. */

    printf("\n");
    printf("%s\n%4s%10.1e\n\n\n", "Estimate of reciprocal of condition number",
           "", rcond);
    /* nag_file_print_matrix_complex_gen_comp (x04dbc), see above. */
    fflush(stdout);
    nag_file_print_matrix_complex_gen_comp(
        order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b, pdb,
        Nag_BracketForm, "%7.4f", "Solution", Nag_IntegerLabels, 0,
        Nag_IntegerLabels, 0, 80, 0, 0, &fail);
    if (fail.code != NE_NOERROR) {
      printf(
          "Error from nag_file_print_matrix_complex_gen_comp (x04dbc).\n%s\n",
          fail.message);
      exit_status = 1;
      goto END;
    }
  } else if (fail.code == NE_POS_DEF) {
    /* The matrix A is not positive definite to working precision */
    printf("%s%3" NAG_IFMT "%s\n\n", "The leading minor of order ", fail.errnum,
           " is not positive definite");
  } else {
    printf("Error from nag_linsys_complex_posdef_band_solve (f04cfc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

END:
  NAG_FREE(clabs);
  NAG_FREE(rlabs);
  NAG_FREE(ab);
  NAG_FREE(b);

  return exit_status;
}

#undef AB
#undef B