lapack-gels-case1.cc (flens/examples/lapack-gels-case1.cc)

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#include <cxxstd/iostream.h>

#include <flens/flens.cxx>

using namespace flens;

using namespace std;

int

main()

{

    typedef GeMatrix<FullStorage<double> >   GeMatrix;

    typedef DenseVector<Array<double> >      DenseVector;

    typedef typename DenseVector::IndexType  IndexType;

    const Underscore<IndexType>  _;

    GeMatrix     A(4, 3);

    DenseVector  b(4);

///

/// Setup the matrix $A$.

///

    A =  1,  2,  3,

         4,  5,  6,

         7,  8,  9,

        10, 11, 13;

///

/// Setup vector $b$

///

    b =  6,

        15,

        24,

        34;

///

/// The least square solution $x$ will be stored in the first three components

/// of vector $b$.  So vectors view come in handy:

///

    auto x = b(_(1,3));

///

/// Solve $\min\limits_{x} \|Ax - b \|$

///

    lapack::ls(NoTrans, A, b);

    cout << "x = " << x << endl;

    return 0;

}