parameters diagonalize_bisection(localized_matrix<double, MATRIX_MAJOR>& mat, double* eigvals,
rokko::parameters const& params) {
rokko::parameters params_out;
char jobz = 'N'; // only eigenvalues
int dim = mat.outerSize();
int ldim_mat = mat.innerSize();
lapack_int m; // output: found eigenvalues
double abstol;
get_key(params, "abstol", abstol);
if (abstol < 0) {
std::cerr << "Error in diagonalize_bisection" << std::endl
<< "abstol is negative value, which means QR method." << std::endl
<< "To use dsyevx as bisection solver, set abstol a positive value" << std::endl;
throw;
}
if (!params.defined("abstol")) { // default: optimal value for bisection method
abstol = 2 * LAPACKE_dlamch('S');
}
params_out.set("abstol", abstol);
char uplow = get_matrix_part(params);
lapack_int il, iu;
double vl, vu;
char range = get_eigenvalues_range(params, vl, vu, il, iu);
std::vector<lapack_int> ifail(dim);
int info;
if(mat.is_col_major())
info = LAPACKE_dsyevx(LAPACK_COL_MAJOR, jobz, range, uplow, dim, &mat(0,0), ldim_mat, vl, vu, il, iu, abstol, &m, eigvals, NULL, ldim_mat, &ifail[0]);
else
info = LAPACKE_dsyevx(LAPACK_ROW_MAJOR, jobz, range, uplow, dim, &mat(0,0), ldim_mat, vl, vu, il, iu, abstol, &m, eigvals, NULL, ldim_mat, &ifail[0]);
if (info) {
std::cerr << "error at dsyevx function. info=" << info << std::endl;
if (info < 0) {
std::cerr << "This means that ";
std::cerr << "the " << abs(info) << "-th argument had an illegal value." << std::endl;
}
exit(1);
}
params_out.set("m", m);
params_out.set("ifail", ifail);
if (params.get_bool("verbose")) {
print_verbose("dsyevx (bisection)", jobz, range, uplow, vl, vu, il, iu, params_out);
}
return params_out;
}
void solve_entire_bi(int n, double *A, double *E, double *Q, char type){
double tol = 0.;
int *isuppz = malloc(2*n*sizeof(int)); assert(isuppz);
int k;
int info = LAPACKE_dsyevx(LAPACK_COL_MAJOR, type, 'A', 'L',
n, A, n, 0., 0., 0, 0, tol, &k, E, Q, n, isuppz);
assert(!info);
free(isuppz);
}
void xx_eig(gsl_matrix *sym, gsl_vector *eval, gsl_matrix *evec, size_t NCOMP ){
// simple Eigen decomposition with embedded cut
size_t NSUB = sym->size1;
lapack_int m=0;
double abstol=-1.0, vl=0.0, vu=0.0;
lapack_int *ifail = (lapack_int *)LAPACKE_malloc( sizeof(lapack_int) * NSUB );
LAPACKE_dsyevx(LAPACK_ROW_MAJOR, 'V', 'I', 'U',
NSUB, sym->data, NSUB, vl, vu, NSUB-NCOMP+1, NSUB,
abstol, &m, eval->data, evec->data, NCOMP, ifail);
}