This program requires a matrix to be the value of ANS. A row and column in the matrix is then requested. The element in this position will be made into a one and other elements in that column will be turned into zeros by applying the elementary row operations.
Since this program requires the matrix to be in the ANS before running, the program can be executed again on the reduced matrix, simply by hitting the ENTER key. This makes it very easy and quick to reduce the entire matrix.
Matrices are returned in fractional form because, as noted earlier, Fractions Are Your Friends.