1 typedef Matrix<float,1,Dynamic> MatrixType; 2 typedef Map<MatrixType> MapType; 3 typedef Map<const MatrixType> MapTypeConst; // a read-only map 4 const int n_dims = 5; 5 6 MatrixType m1(n_dims), m2(n_dims); 7 m1.setRandom(); 8 m2.setRandom(); 9 float *p = &m2(0); // get the address storing the data for m2 10 MapType m2map(p,m2.size()); // m2map shares data with m2 11 MapTypeConst m2mapconst(p,m2.size()); // a read-only accessor for m2 12 13 cout << "m1: " << m1 << endl; 14 cout << "m2: " << m2 << endl; 15 cout << "Squared euclidean distance: " << (m1-m2).squaredNorm() << endl; 16 cout << "Squared euclidean distance, using map: " << 17 (m1-m2map).squaredNorm() << endl; 18 m2map(3) = 7; // this will change m2, since they share the same array 19 cout << "Updated m2: " << m2 << endl; 20 cout << "m2 coefficient 2, constant accessor: " << m2mapconst(2) << endl; 21 /* m2mapconst(2) = 5; */ // this yields a compile-time error 22
