#include <cxxstd/iostream.h>
#include <flens/flens.cxx> using namespace flens; using namespace std; int main() { GeMatrix<FullStorage<double> > A(3, 3); DenseVector<Array<double> > b(3); /// /// Setup the raw data. /// A = 2, 0, 0, 1, 2, 0, 0, 1, 2; b = 1, 2, 3; /// /// $S$ is a symmetric matrix view constructed from the lower triangular /// part of $A$. Note that $S$ only references data from $A$. /// auto S = A.lower().symmetric(); cout << "S = " << S << endl; cout << "b = " << b << endl; /// /// - Computes the Cholesky factorization $S = L L^T$ where $L$ is lower /// triangular. Matrix $S$ (i.e. the lower triangular part of $A$) gets /// overwritten with $L$. /// - Solves $Lu=b$ and then $L^T x = u$. Vector $b$ gets overwritten with $x$. /// int info = lapack::posv(S, b); /// /// If `info` is not zero the factorization could not be computed as the matrix /// was singular. /// if (info!=0) { cerr << "S is singular" << endl; return info; } cout << "inv(S)*b = " << b << endl; return 0; } |