update doc snippets

doc/snippets/LU_computeImage.cpp

@@ -1,13 +0,0 @@
-MatrixXd m(3,3);
-m << 1,1,0,
-     1,3,2,
-     0,1,1;
-cout << "Here is the matrix m:" << endl << m << endl;
-LU<Matrix3d> lu(m);
-// allocate the matrix img with the correct size to avoid reallocation
-MatrixXd img(m.rows(), lu.rank());
-lu.computeImage(&img);
-cout << "Notice that the middle column is the sum of the two others, so the "
-     << "columns are linearly dependent." << endl;
-cout << "Here is a matrix whose columns have the same span but are linearly independent:"
-     << endl << img << endl;

doc/snippets/LU_computeKernel.cpp

@@ -1,10 +0,0 @@
-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;

doc/snippets/LU_image.cpp

@@ -6,4 +6,4 @@ cout << "Here is the matrix m:" << endl << m << endl;
 cout << "Notice that the middle column is the sum of the two others, so the "
      << "columns are linearly dependent." << endl;
 cout << "Here is a matrix whose columns have the same span but are linearly independent:"
-     << endl << m.lu().image() << endl;
+     << endl << m.lu().image(m) << endl;