lapack-getri.cc (flens/examples/lapack-getri.cc)

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#include <cxxstd/iostream.h>

#include <flens/flens.cxx>

using namespace flens;

using namespace std;

int

main()

{

    GeMatrix<FullStorage<double> >   A(3,3);

    DenseVector<Array<int> >         piv(3);

///

/// Setup the toy example.

///

    A = 1, 2, 3,

        4, 5, 6,

        7, 8, 1;

    cout << "A = " << A << endl;

///

/// Compute the $LU$ factoriation of $A$.

///

    int info = lapack::trf(A, piv);

///

/// If `info` is not zero then the matrix was singular.  More precise, the

/// upper triangular matrix $U$ computed by `trf` is exactly singular.

///

    if (info!=0) {

        cerr << "A is singular" << endl;

        return info;

    }

///

///  Compute $A^{-1}$ from the $LU$ factorization of $A$.

///

    lapack::tri(A, piv);

    cout << "inv(A) = " << A << endl;

    return 0;

}