tut05-page01-example2.cc (flens/examples/tut05-page01-example2.cc)

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#include <cxxstd/complex.h>

#include <cxxstd/iostream.h>

///

/// Define `USE_CXXLAPACK` before you include the FLENS headers

///

#ifndef USE_CXXLAPACK

#define USE_CXXLAPACK

#endif

#include <flens/flens.cxx>

using namespace std;

using namespace flens;

///

/// Elements are now defined to be *complex*

///

typedef complex<double>   T;

int

main()

{

    typedef GeMatrix<FullStorage<T> >           Matrix;

    typedef DenseVector<Array<T> >              Vector;

    typedef Matrix::IndexType                   IndexType;

    typedef DenseVector<Array<IndexType> >      IndexVector;

    const IndexType n = 3;

    Matrix         A(n,n);

    Vector         b(n);

    IndexVector    piv(n);

    A = T(1, 0), T( 1,-1), T(  2,20),

        T(0, 1), T( 1, 2), T(-10, 8),

        T(0,-1), T(-1, 1), T( 40, 6);

    b = T( 1, 0),

        T(-1, 1),

        T(-2,-1);

    cerr << "A = " << A << endl;

    cerr << "b = " << b << endl;

///

/// We use __cxxlapack::getrf__ as we did in the previous example ...

///

/// :links: __cxxlapack::getrf__ -> file:cxxlapack/interface/getrf.h

///

    IndexType info = cxxlapack::getrf(A.numRows(),

                                      A.numCols(),

                                      A.data(),

                                      A.leadingDimension(),

                                      piv.data());

    if (info==0) {

///

///     ... and also __cxxlapack::getrs__.

///

///     :links: __cxxlapack::getrs__ -> file:cxxlapack/interface/getrs.h

///

        cxxlapack::getrs(lapack::getF77Char(NoTrans),

                         A.numRows(),

                         IndexType(1),

                         A.data(),

                         A.leadingDimension(),

                         piv.data(),

                         b.data(),

                         b.length());

        cerr << "x = " << b << endl;

    } else {

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

    }

}