/* nag_lapackeig_zgeev (f08nnc) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.1, 2024.
*/
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Scalars */
Integer exit_status = 0, i, j, n, pda, pdvr;
/* Arrays */
Complex *a = 0, *vr = 0, *w = 0;
Complex dummy[1];
/* Nag Types */
NagError fail;
Nag_OrderType order;
#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
#define VR(I, J) vr[(J)*pdvr + I]
order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
#define VR(I, J) vr[(I)*pdvr + J]
order = Nag_RowMajor;
#endif
INIT_FAIL(fail);
printf("nag_lapackeig_zgeev (f08nnc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%*[^\n]", &n);
pda = n;
pdvr = n;
/* Allocate memory */
if (!(a = NAG_ALLOC(n * n, Complex)) || !(vr = NAG_ALLOC(n * n, Complex)) ||
!(w = NAG_ALLOC(n, Complex))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
/* Read the matrix A from data file */
for (i = 1; i <= n; ++i)
for (j = 1; j <= n; ++j)
scanf(" ( %lf , %lf )", &A(i, j).re, &A(i, j).im);
scanf("%*[^\n]");
/* Compute the eigenvalues and right eigenvectors of A
using nag_lapackeig_zgeev (f08nnc). */
nag_lapackeig_zgeev(order, Nag_NotLeftVecs, Nag_RightVecs, n, a, pda, w,
dummy, 1, vr, pdvr, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_lapackeig_zgeev (f08nnc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Print eigenvalues and right eigenvectors. */
for (j = 0; j < n; ++j) {
printf("\nEigenvalue %3" NAG_IFMT " = ", j + 1);
if (w[j].im == 0.0)
printf("%13.4e\n", w[j].re);
else
printf(" (%13.4e, %13.4e)\n", w[j].re, w[j].im);
printf("\nEigenvector %2" NAG_IFMT "\n", j + 1);
for (i = 0; i < n; ++i)
printf("%18s(%13.4e, %13.4e)\n", "", VR(i, j).re, VR(i, j).im);
printf("\n");
}
END:
NAG_FREE(a);
NAG_FREE(vr);
NAG_FREE(w);
return exit_status;
}
#undef A