Minimum, messy code

lib/utils.cpp

@@ -70,4 +70,47 @@ std::string concatpath(const std::string &left, const std::string &right)
     }
 }
 
+void print_sp_matrix_structure(const arma::sp_cx_mat &A)
+{
+    using namespace std;
+    using namespace arma;
+
+    // Declare a C-style 2D array of strings.
+    string S[A.n_rows][A.n_cols];
+
+    // Initialise all the strings to " ".
+    for (int i = 0; i < A.n_rows; i++) {
+        for (int j = 0; j < A.n_cols; j++) {
+            S[i][j] = " ";
+        }
+    }
+
+    // Next, we want to set the string to a dot at each non-zero element.
+    // To do this we use the special loop iterator from the sp_cx_mat class
+    // to help us loop over only the non-zero matrix elements.
+    sp_cx_mat::const_iterator it = A.begin();
+    sp_cx_mat::const_iterator it_end = A.end();
+
+    int nnz = 0;
+    for (; it != it_end; ++it) {
+        S[it.row()][it.col()] = "•";
+        nnz++;
+    }
+
+    // Finally, print the matrix to screen.
+    cout << endl;
+    for (int i = 0; i < A.n_rows; i++) {
+        cout << "| ";
+        for (int j = 0; j < A.n_cols; j++) {
+            cout << S[i][j] << " ";
+        }
+        cout << "|\n";
+    }
+
+    cout << endl;
+    cout << "matrix size: " << A.n_rows << "x" << A.n_cols << endl;
+    cout << "non-zero elements: " << nnz << endl;
+    cout << endl;
+}
+
 } // namespace utils