/* nag_dgbequ (f07bfc) 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>
#include <nagx02.h>

int main(void)
{

/* Scalars */
double amax, big, colcnd, rowcnd, small;
Integer exit_status = 0, i, j, kl, ku, n, pdab;

/* Arrays */
double *ab = 0, *c = 0, *r = 0;

/* Nag Types */
NagError fail;
Nag_OrderType order;
Nag_Boolean scaled = Nag_FALSE;

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

INIT_FAIL(fail);

printf("nag_dgbequ (f07bfc) Example Program Results\n\n");
fflush(stdout);

/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &kl, &ku);
if (n < 0 || kl < 0 || ku < 0) {
printf("Invalid n or kl or ku\n");
exit_status = 1;
goto END;
}
/* Allocate arrays */
pdab = kl + ku + 1;
if (!(ab = NAG_ALLOC(pdab * n, double)) ||
!(c = NAG_ALLOC(n, double)) || !(r = NAG_ALLOC(n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Read the band matrix A 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]");

/* Print the matrix A using nag_band_real_mat_print (x04cec). */
fflush(stdout);
nag_band_real_mat_print(order, n, n, kl, ku, 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 = 1;
goto END;
}

printf("\n");
/* Compute row and column scaling factors using nag_dgbequ (f07bfc). */
nag_dgbequ(order, n, n, kl, ku, ab, pdab, r, c, &rowcnd, &colcnd, &amax,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_dgbequ (f07bfc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print rowcnd, colcnd, amax and the scale factors */
printf("rowcnd = %10.1e, colcnd = %10.1e, amax = %10.1e\n\n", rowcnd,
colcnd, amax);
printf("Row scale factors\n");
for (i = 1; i <= n; ++i)
printf("%11.2e%s", r[i - 1], i % 7 == 0 ? "\n" : " ");

printf("\n\nColumn scale factors\n");
for (i = 1; i <= n; ++i)
printf("%11.2e%s", c[i - 1], i % 7 == 0 ? "\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 (colcnd < 0.1) {
scaled = Nag_TRUE;
/* column scale A */
for (j = 1; j <= n; ++j)
for (i = MAX(1, j - ku); i <= MIN(n, j + kl); ++i)
AB(i, j) *= c[j - 1];
}
if (rowcnd < 0.1 || amax < small || amax > big) {
/* row scale A */
scaled = Nag_TRUE;
for (j = 1; j <= n; ++j)
for (i = MAX(1, j - ku); i <= MIN(n, j + kl); ++i)
AB(i, j) *= r[i - 1];
}
if (scaled) {
/* Print the row and column scaled matrix using
* nag_band_real_mat_print (x04cec).
*/
printf("\n\n");
fflush(stdout);
nag_band_real_mat_print(order, n, n, kl, ku, 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 = 1;
goto END;
}
}
END:
NAG_FREE(ab);
NAG_FREE(c);
NAG_FREE(r);

return exit_status;
}