1 #include <iostream>
 2 ///
 3 ///  With header __flens.cxx__ all of FLENS gets included.
 4 ///
 5 ///  :links:  __flens.cxx__ -> file:flens/flens.cxx
 6 #include <flens/flens.cxx>
 7 
 8 using namespace std;
 9 using namespace flens;
10 
11 typedef double   T;
12 
13 int
14 main()
15 {
16     ///
17     ///  Define some convenient typedefs for the matrix/vector types
18     ///  of our system of linear equations.
19     ///
20     typedef GeMatrix<FullStorage<T> >           Matrix;
21     typedef DenseVector<Array<T> >              Vector;
22 
23     ///
24     ///  We also need an extra vector type for the pivots.  The type of the
25     ///  pivots is taken for the system matrix.
26     ///
27     typedef Matrix::IndexType                   IndexType;
28     typedef DenseVector<Array<IndexType> >      IndexVector;
29 
30     ///
31     ///  Define an underscore operator for convenient matrix slicing
32     ///
33     const Underscore<IndexType> _;
34 
35     ///
36     ///  Set up the baby problem ...
37     ///
38     const IndexType m = 4,
39                     n = 5;
40 
41     Matrix            Ab(m, n);
42     IndexVector       piv(m);
43 
44     Ab =  2,   3,  -1,   0,  20,
45          -6,  -5,   0,   2, -33,
46           2,  -5,   6,  -6, -43,
47           4,   6,   2,  -3,  49;
48 
49     cout << "Ab = " << Ab << endl;
50 
51     ///
52     /// Compute the $LU$ factorization with __lapack::trf__
53     ///
54     lapack::trf(Ab, piv);
55 
56     ///
57     ///  Solve the system of linear equation $Ax =B$ using __blas::sm__
58     ///
59     const auto A = Ab(_,_(1,m));
60     auto       B = Ab(_,_(m+1,n));
61 
62     blas::sm(Left, NoTrans, T(1), A.upper(), B);
63 
64     cout << "X = " << B << endl;
65 }
66 
67 ///
68 ///  :links: __lapack::trf__ -> file:flens/lapack/gesv/trf.h
69 ///          __blas::sm__ -> file:flens/blas/level3/sm.h
70 ///