```/* nag_linsys_complex_square_solve (f04cac) Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
*
* Mark 27.0, 2019.
*/

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

int main(void)
{
/* Scalars */
double errbnd, rcond;
Integer exit_status, i, j, n, nrhs, pda, pdb;

/* Arrays */
char *clabs = 0, *rlabs = 0;
Complex *a = 0, *b = 0;
Integer *ipiv = 0;

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

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

exit_status = 0;
INIT_FAIL(fail);

printf("nag_linsys_complex_square_solve (f04cac) Example Program Results\n\n");

/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &nrhs);
if (n > 0 && nrhs > 0) {
/* Allocate memory */
if (!(clabs = NAG_ALLOC(2, char)) ||
!(rlabs = NAG_ALLOC(2, char)) ||
!(a = NAG_ALLOC(n * n, Complex)) ||
!(b = NAG_ALLOC(n * nrhs, Complex)) ||
!(ipiv = NAG_ALLOC(8, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
#ifdef NAG_COLUMN_MAJOR
pda = n;
pdb = n;
#else
pda = n;
pdb = nrhs;
#endif

/* Read A and B from data file */
}
else {
printf("%s\n", "NMAX and/or NRHSMX too small");
exit_status = 1;
return exit_status;
}

for (i = 1; i <= n; ++i) {
for (j = 1; j <= n; ++j) {
scanf(" ( %lf , %lf )", &A(i, j).re, &A(i, j).im);
}
}
scanf("%*[^\n] ");

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_square_solve (f04cac).
* Computes the solution and error-bound to a complex system
* of linear equations
*/
nag_linsys_complex_square_solve(order, n, nrhs, a, pda, ipiv, 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");
printf("%s\n%8s%10.1e\n", "Estimate of condition number", "",
1.0 / rcond);
printf("\n\n");
printf("%s\n%8s%10.1e\n\n",
"Estimate of error bound for computed solutions", "", errbnd);
}
else if (fail.code == NE_RCOND) {
/* Matrix is numerically singular.  Print estimate of */
/* reciprocal of condition number and solution */

printf("\n");
printf("%s\n%8s%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, 0,
"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_SINGULAR) {
/* The upper triangular matrix U is exactly singular.  Print */
/* details of factorization */
printf("\n");
/* 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, n, a, pda, Nag_BracketForm, "%7.4f",
"Details of factorization",
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;
}

/* Print pivot indices */
printf("\n");
printf("%s\n", "Pivot indices");
printf("%1s", "");
for (i = 1; i <= n; ++i) {
printf("%11" NAG_IFMT "%s", ipiv[i - 1], i % 7 == 0
|| i == n ? "\n" : " ");
}
printf("\n");
}
else {
printf("Error from nag_linsys_complex_square_solve (f04cac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
END:
NAG_FREE(clabs);
NAG_FREE(rlabs);
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(ipiv);

return exit_status;
}
```