```/* nag_zpbsvx (f07hpc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.2, 2017.
*/

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagf07.h>

int main(void)
{
/* Scalars */
double rcond;
Integer exit_status = 0, i, j, kd, n, nrhs, pdab, pdafb, pdb, pdx;

/* Arrays */
Complex *ab = 0, *afb = 0, *b = 0, *x = 0;
double *berr = 0, *ferr = 0, *s = 0;
char nag_enum_arg[40];

/* Nag Types */
NagError fail;
Nag_UploType uplo;
Nag_OrderType order;
Nag_EquilibrationType equed;

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

printf("nag_zpbsvx (f07hpc) 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) {
printf("%s\n", "Invalid n or kd or nrhs");
exit_status = 1;
goto END;
}
scanf(" %39s%*[^\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);

/* Allocate memory */
if (!(ab = NAG_ALLOC((kd + 1) * n, Complex)) ||
!(afb = NAG_ALLOC((kd + 1) * n, Complex)) ||
!(b = NAG_ALLOC(n * nrhs, Complex)) ||
!(x = NAG_ALLOC(n * nrhs, Complex)) ||
!(berr = NAG_ALLOC(nrhs, double)) ||
!(ferr = NAG_ALLOC(nrhs, double)) || !(s = NAG_ALLOC(n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
pdab = kd + 1;
pdafb = kd + 1;
#ifdef NAG_COLUMN_MAJOR
pdb = n;
pdx = n;
#else
pdb = nrhs;
pdx = nrhs;
#endif

/* 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_UPPER(i, j).re, &AB_UPPER(i, j).im);
else
for (i = 1; i <= n; ++i)
for (j = MAX(1, i - kd); j <= i; ++j)
scanf(" ( %lf , %lf )", &AB_LOWER(i, j).re, &AB_LOWER(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 using nag_zpbsvx (f07hpc). */
nag_zpbsvx(order, Nag_EquilibrateAndFactor, uplo, n, kd, nrhs, ab, pdab,
afb, pdafb, &equed, s, b, pdb, x, pdx, &rcond, ferr, berr,
&fail);
if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) {
printf("Error from nag_zpbsvx (f07hpc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print solution using nag_gen_complx_mat_print_comp (x04dbc). */
fflush(stdout);
nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
nrhs, x, pdx, Nag_BracketForm, "%7.4f",
"Solution(s)", Nag_IntegerLabels, 0,
Nag_IntegerLabels, 0, 80, 0, 0, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Print error bounds, condition number and the form of equilibration */
printf("\nBackward errors (machine-dependent)\n");
for (j = 0; j < nrhs; ++j)
printf("%11.1e%s", berr[j], j % 7 == 6 ? "\n" : " ");

printf("\n\nEstimated forward error bounds (machine-dependent)\n");
for (j = 0; j < nrhs; ++j)
printf("%11.1e%s", ferr[j], j % 7 == 6 ? "\n" : " ");

printf("\n\nEstimate of reciprocal condition number\n%11.1e\n\n", rcond);
if (equed == Nag_NoEquilibration)
printf("A has not been equilibrated\n");
else if (equed == Nag_RowAndColumnEquilibration)
printf("A has been row and column scaled as diag(S)*A*diag(S)\n");
if (fail.code == NE_SINGULAR) {
printf("Error from nag_zpbsvx (f07hpc).\n%s\n", fail.message);
exit_status = 1;
}
END:
NAG_FREE(ab);
NAG_FREE(afb);
NAG_FREE(b);
NAG_FREE(x);
NAG_FREE(berr);
NAG_FREE(ferr);
NAG_FREE(s);

return exit_status;
}

#undef AB_UPPER
#undef AB_LOWER
#undef B
```