qpms/tests/tbeyn_gsl.c

43 lines
1.2 KiB
C

#include <qpms/beyn.h>
#include <stdio.h>
// Matrix as in Beyn, section 4.11
int M_function(gsl_matrix_complex *target, complex double z, void *no_params) {
int m = target->size1;
gsl_complex d = gsl_complex_fromstd( 2*m - 4*z / (6*m) );
gsl_complex od = gsl_complex_fromstd( -(double)m - z / (6*m) );
gsl_matrix_complex_set_zero(target);
for (int i = 0; i < m; ++i) {
gsl_matrix_complex_set(target, i, i, d);
if(i > 0) gsl_matrix_complex_set(target, i, i-1, od);
if(i < m - 1) gsl_matrix_complex_set(target, i, i+1, od);
}
gsl_matrix_complex_set(target, m-1, m-1, gsl_complex_fromstd(gsl_complex_tostd(d)/2 + z/(z-1)));
return 0;
}
int main() {
complex double z0 = 150+2*I;
double Rx = 148, Ry = 148;
int L = 10, N = 50, dim = 400;
beyn_contour_t *contour = beyn_contour_ellipse(z0, Rx, Ry, N);
beyn_result_gsl_t *result =
beyn_solve_gsl(dim, L, M_function, NULL /*M_inv_Vhat_function*/, NULL /*params*/,
contour, 1e-4, 1e-4);
printf("Found %zd eigenvalues:\n", result->neig);
for (size_t i = 0; i < result->neig; ++i) {
gsl_complex eig = gsl_vector_complex_get(result->eigval, i);
printf("%zd: %g%+gj\n", i, GSL_REAL(eig), GSL_IMAG(eig));
}
free(contour);
beyn_result_gsl_free(result);
return 0;
}