```/* nag_dgbsvx (f07bbc) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 23, 2011.
*/

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

int main(void)
{

/* Scalars */
double                growth_factor, rcond;
Integer               exit_status = 0, i, j, kl, ku, n, nrhs, pdab,
pdafb, pdb, pdx;

/* Arrays */
double                *ab = 0, *afb = 0, *b = 0, *berr = 0, *c = 0;
double                *ferr = 0, *r = 0, *x = 0;
Integer               *ipiv = 0;

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

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

INIT_FAIL(fail);

printf("nag_dgbsvx (f07bbc) Example Program Results\n\n");

/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%ld%ld%ld%ld%*[^\n]", &n, &nrhs,
&kl, &ku);
if (n < 0 || kl < 0 || ku < 0 || nrhs < 0)
{
printf("Invalid n, kl, ku or nrhs\n");
exit_status = 1;
goto END;
}

pdab = kl+ku+1;
pdafb = 2*kl+ku+1;
#ifdef NAG_COLUMN_MAJOR
pdx = n;
pdb = n;
#else
pdx = nrhs;
pdb = nrhs;
#endif

/* Allocate memory */
if (!(ab   = NAG_ALLOC(pdab * n, double)) ||
!(afb  = NAG_ALLOC(pdafb * n, double)) ||
!(b    = NAG_ALLOC(n*nrhs, double)) ||
!(berr = NAG_ALLOC(nrhs, double)) ||
!(c    = NAG_ALLOC(n, double)) ||
!(ferr = NAG_ALLOC(nrhs, double)) ||
!(r    = NAG_ALLOC(n, double)) ||
!(x    = NAG_ALLOC(n*nrhs, double)) ||
!(ipiv = NAG_ALLOC(n, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Read the band matrix A and B from data file */
for (i = 1; i <= n; ++i)
for (j = MAX(i - kl, 1); j <= MIN(i + ku, n); ++j)
scanf("%lf", &AB(i, j));
scanf("%*[^\n]");

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_dgbsvx (f07bbc). */
nag_dgbsvx(order, Nag_EquilibrateAndFactor, Nag_NoTrans, n, kl, ku, nrhs, ab,
pdab, afb, pdafb, ipiv, &equed, r, c, b, pdb, x, pdx, &rcond,
ferr, berr, &growth_factor, &fail);
if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR)
{
printf("Error from nag_dgbsvx (f07bbc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print solution using nag_gen_real_mat_print (x04cac). */
fflush(stdout);
nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs,
x, pdx, "Solution(s)", 0, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Print error bounds, condition number, the form of equilibration
* and the pivot growth factor
*/
printf("\nBackward errors (machine-dependent)\n");
for (j = 1; j <= nrhs; ++j)
printf("%11.1e%s", berr[j - 1], j%7 == 0?"\n":" ");

printf("\n\nEstimated forward error bounds (machine-dependent)\n");
for (j = 1; j <= nrhs; ++j)
printf("%11.1e%s", ferr[j - 1], j%7 == 0?"\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_RowEquilibration)
printf("A has been row scaled as diag(R)*A\n");
else if (equed == Nag_ColumnEquilibration)
printf("A has been column scaled as A*diag(C)\n");
else if (equed == Nag_RowAndColumnEquilibration)
printf("A has been row and column scaled as diag(R)*A*diag(C)\n");

printf("\nEstimate of reciprocal pivot growth factor\n%11.1e\n",
growth_factor);

if (fail.code == NE_SINGULAR)
printf("Error from nag_dgbsvx (f07bbc).\n%s\n", fail.message);
END:
NAG_FREE(ab);
NAG_FREE(afb);
NAG_FREE(b);
NAG_FREE(berr);
NAG_FREE(c);
NAG_FREE(ferr);
NAG_FREE(r);
NAG_FREE(x);
NAG_FREE(ipiv);

return exit_status;
}

#undef AB
#undef B
```