```/* nag_dpbequ (f07hfc) 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>
#include <nagx02.h>

int main(void)
{

/* Scalars */
double amax, big, scond, small;
Integer exit_status = 0, i, j, kd, kd1, kd2, n, pdab;

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

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

#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]
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]
order = Nag_RowMajor;
#endif

INIT_FAIL(fail);

printf("nag_dpbequ (f07hfc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &n, &kd);
if (n < 0 || kd < 0) {
printf("Invalid n or kd\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);

pdab = kd + 1;
/* Allocate memory */
if (!(ab = NAG_ALLOC((kd + 1) * n, double)) || !(s = NAG_ALLOC(n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Read the upper or lower triangular part of the band matrix A
* from data file.
*/
if (uplo == Nag_Upper) {
kd1 = 0;
kd2 = kd;
for (i = 1; i <= n; ++i)
for (j = i; j <= MIN(n, i + kd); ++j)
scanf("%lf", &AB_UPPER(i, j));
}
else {
kd1 = kd;
kd2 = 0;
for (i = 1; i <= n; ++i)
for (j = MAX(1, i - kd); j <= i; ++j)
scanf("%lf", &AB_LOWER(i, j));
}
scanf("%*[^\n]");

/* Print the matrix A using nag_band_real_mat_print (x04cec). */

fflush(stdout);
nag_band_real_mat_print(order, n, n, kd1, kd2, ab, pdab, "Matrix A", 0,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_band_real_mat_print (x04cec).\n%s\n",
fail.message);
exit_status = 2;
goto END;
}
printf("\n");

/* Compute diagonal scaling factors using nag_dpbequ (f07hfc). */
nag_dpbequ(order, uplo, n, kd, ab, pdab, s, &scond, &amax, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_dpbequ (f07hfc).\n%s\n", fail.message);
exit_status = 3;
goto END;
}
/* Print scond, amax and the scale factors */
printf("scond = %10.1e, amax = %10.1e\n", scond, amax);
printf("\nDiagonal scaling factors\n");
for (i = 0; i < n; ++i)
printf("%11.1e%s", s[i], i % 7 == 6 ? "\n" : " ");
printf("\n\n");

/* Compute values close to underflow and overflow using
* nag_real_safe_small_number (x02amc), nag_machine_precision (x02ajc) and
* nag_real_base (x02bhc)
*/
small = nag_real_safe_small_number / (nag_machine_precision *
nag_real_base);
big = 1.0 / small;
if (scond < 0.1 || amax < small || amax > big) {
/* Scale A */
if (uplo == Nag_Upper)
for (j = 1; j <= n; ++j)
for (i = MAX(1, j - kd); i <= j; ++i)
AB_UPPER(i, j) *= s[i - 1] * s[j - 1];
else
for (j = 1; j <= n; ++j)
for (i = j; i <= MIN(n, j + kd); ++i)
AB_LOWER(i, j) *= s[i - 1] * s[j - 1];

/* Print the scaled matrix using nag_band_real_mat_print (x04cec). */
fflush(stdout);
nag_band_real_mat_print(order, n, n, kd1, kd2, ab, pdab, "Scaled matrix",
0, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_band_real_mat_print (x04cec).\n%s\n",
fail.message);
exit_status = 4;
goto END;
}
}
END:
NAG_FREE(ab);
NAG_FREE(s);

return exit_status;
}

#undef AB_UPPER
#undef AB_LOWER
```