```/* nag_dpbsv (f07hac) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.1, 2017.
*/
#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagf07.h>

int main(void)
{

/* Scalars */
Integer exit_status = 0, i, j, kd, n, nrhs, pdb, pdab;

/* Arrays */
double *ab = 0, *b = 0;
char nag_enum_arg[40];

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

#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_dpbsv (f07hac) 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 || nrhs < 0 || kd < 0) {
printf("Invalid n, kd or nrhs\n");
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, double)) ||
!(b = NAG_ALLOC(n * nrhs, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

pdab = kd + 1;
#ifdef NAG_COLUMN_MAJOR
pdb = n;
#else
pdb = 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", &AB_UPPER(i, j));
else
for (i = 1; i <= n; ++i)
for (j = MAX(1, i - kd); j <= i; ++j)
scanf("%lf", &AB_LOWER(i, j));
scanf("%*[^\n]");

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

/* Solve the equations Ax = b for x using nag_dpbsv (f07hac). */
nag_dpbsv(order, uplo, n, kd, nrhs, ab, pdab, b, pdb, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_dpbsv (f07hac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Print solution */
printf("Solution\n");
for (i = 1; i <= n; ++i) {
for (j = 1; j <= nrhs; ++j)
printf("%11.4f%s", B(i, j), j % 7 == 0 ? "\n" : " ");
printf("\n");
}

/* Print details of factorization */
printf("\n");
fflush(stdout);
if (uplo == Nag_Upper)
nag_band_real_mat_print(order, n, n, 0, kd, ab, pdab, "Cholesky factor U",
0, &fail);
else
nag_band_real_mat_print(order, n, n, kd, 0, ab, pdab, "Cholesky factor L",
0, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_band_real_mat_print (x04cec).\n%s\n",
fail.message);
exit_status = 1;
}
END:
NAG_FREE(ab);
NAG_FREE(b);

return exit_status;
}

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