/* nag_lapackeig_zgbbrd (f08lsc) Example Program.
*
* Copyright 2022 Numerical Algorithms Group.
*
* Mark 28.3, 2022.
*/
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Scalars */
Integer i, j, kl, ku, m, n, ncc, pdab, pdc, pdq, pdpt;
Integer d_len, e_len;
Integer exit_status = 0;
NagError fail;
Nag_OrderType order;
/* Arrays */
Complex *ab = 0, *c = 0, *pt = 0, *q = 0;
double *d = 0, *e = 0;
#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_lapackeig_zgbbrd (f08lsc) Example Program Results\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT
"%*[^\n] ",
&m, &n, &kl, &ku, &ncc);
#ifdef NAG_COLUMN_MAJOR
pdab = kl + ku + 1;
pdq = m;
pdpt = n;
pdc = m;
#else
pdab = kl + ku + 1;
pdq = m;
pdpt = n;
pdc = MAX(1, ncc);
#endif
d_len = MIN(m, n);
e_len = MIN(m, n) - 1;
/* Allocate memory */
if (!(ab = NAG_ALLOC((kl + ku + 1) * m, Complex)) ||
!(c = NAG_ALLOC(m * MAX(1, ncc), Complex)) ||
!(d = NAG_ALLOC(d_len, double)) || !(e = NAG_ALLOC(e_len, double)) ||
!(pt = NAG_ALLOC(n * n, Complex)) || !(q = NAG_ALLOC(m * m, Complex))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
/* Read A from data file */
for (i = 1; i <= m; ++i) {
for (j = MAX(1, i - kl); j <= MIN(n, i + ku); ++j)
scanf(" ( %lf , %lf )", &AB(i, j).re, &AB(i, j).im);
}
scanf("%*[^\n] ");
/* Reduce A to bidiagonal form */
/* nag_lapackeig_zgbbrd (f08lsc).
* Reduction of complex rectangular band matrix to upper
* bidiagonal form
*/
nag_lapackeig_zgbbrd(order, Nag_DoNotForm, m, n, ncc, kl, ku, ab, pdab, d, e,
q, pdq, pt, pdpt, c, pdc, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_lapackeig_zgbbrd (f08lsc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Print bidiagonal form */
printf("\nDiagonal\n");
for (i = 1; i <= MIN(m, n); ++i)
printf("%9.4f%s", d[i - 1], i % 8 == 0 ? "\n" : " ");
if (m >= n)
printf("\nSuperdiagonal\n");
else
printf("\nSubdiagonal\n");
for (i = 1; i <= MIN(m, n) - 1; ++i)
printf("%9.4f%s", e[i - 1], i % 8 == 0 ? "\n" : " ");
printf("\n");
END:
NAG_FREE(ab);
NAG_FREE(c);
NAG_FREE(d);
NAG_FREE(e);
NAG_FREE(pt);
NAG_FREE(q);
return exit_status;
}