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19.7 Querying

— Function: bool is_identity (void)

Returns true if *this is the identity Transform, otherwise false. This function has both a const and a non-const version. In the non-const version, clean() is called on *this before comparing the elements of matrix with 1 (for the main diagonal) and 0 (for the other elements). In the const version, *this is copied, clean() is called on the copy, and the elements of the copy's matrix are compared with 0 and 1.

const function: real get_element (const unsigned short row, const unsigned short col)

Returns the value stored in the element of matrix indicated by the arguments.

          Transform t;
          t.shift(1, 2, 3);
          t.scale(2.5, -1.2, 4);
          t.rotate(30, 15, 60);
          t.show("t:");
          -| t:
              1.21    2.09   0.647       0
             0.822  -0.654    0.58       0
             -2.18   0.224    3.35       0
             -3.69    1.45    11.8       1
          cout << t.get_element(2, 1);
          -| 0.224