diff options
author | Gael Guennebaud <g.gael@free.fr> | 2012-06-20 09:28:32 +0200 |
---|---|---|
committer | Gael Guennebaud <g.gael@free.fr> | 2012-06-20 09:28:32 +0200 |
commit | 52dce0c126e67583a349e87a3f5eedee9de92dc7 (patch) | |
tree | 6f27c66cecfec258f22d096835424d6fa324f9fa /doc/special_examples/Tutorial_sparse_example.cpp | |
parent | 882912b85f7ea310fd76689d7e55b8f88e6d3cab (diff) |
significantly extend the tutorial of sparse matrices
Diffstat (limited to 'doc/special_examples/Tutorial_sparse_example.cpp')
-rw-r--r-- | doc/special_examples/Tutorial_sparse_example.cpp | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/doc/special_examples/Tutorial_sparse_example.cpp b/doc/special_examples/Tutorial_sparse_example.cpp new file mode 100644 index 000000000..002f19f01 --- /dev/null +++ b/doc/special_examples/Tutorial_sparse_example.cpp @@ -0,0 +1,32 @@ +#include <Eigen/Sparse> +#include <vector> + +typedef Eigen::SparseMatrix<double> SpMat; // declares a column-major sparse matrix type of double +typedef Eigen::Triplet<double> T; + +void buildProblem(std::vector<T>& coefficients, Eigen::VectorXd& b, int n); +void saveAsBitmap(const Eigen::VectorXd& x, int n, const char* filename); + +int main(int argc, char** argv) +{ + int n = 300; // size of the image + int m = n*n; // number of unknows (=number of pixels) + + // Assembly: + std::vector<T> coefficients; // list of non-zeros coefficients + Eigen::VectorXd b(m); // the right hand side-vector resulting from the constraints + buildProblem(coefficients, b, n); + + SpMat A(m,m); + A.setFromTriplets(coefficients.begin(), coefficients.end()); + + // Solving: + Eigen::SimplicialCholesky<SpMat> chol(A); // performs a Cholesky factorization of A + Eigen::VectorXd x = chol.solve(b); // use the factorization to solve for the given right hand side + + // Export the result to a file: + saveAsBitmap(x, n, argv[1]); + + return 0; +} + |