Complete LU documentation
diff --git a/doc/snippets/LU_computeKernel.cpp b/doc/snippets/LU_computeKernel.cpp
new file mode 100644
index 0000000..b08f7f1
--- /dev/null
+++ b/doc/snippets/LU_computeKernel.cpp
@@ -0,0 +1,10 @@
+MatrixXf m = MatrixXf::Random(3,5);
+cout << "Here is the matrix m:" << endl << m << endl;
+LU<MatrixXf> lu(m);
+// allocate the matrix ker with the correct size to avoid reallocation
+MatrixXf ker(m.rows(), lu.dimensionOfKernel());
+lu.computeKernel(&ker);
+cout << "Here is a matrix whose columns form a basis of the kernel of m:"
+ << endl << ker << endl;
+cout << "By definition of the kernel, m*ker is zero:"
+ << endl << m*ker << endl;