class SparseFieldMatrix extends AbstractFieldMatrix<T> {

    @Override
    public T getEntry(int row, int column) {
        checkRowIndex(row);
        checkColumnIndex(column);
        return entries.get(computeKey(row, column));
    }

    public  SparseFieldMatrix(final Field<T> field);
    public  SparseFieldMatrix(final Field<T> field,
                             final int rowDimension, final int columnDimension);
    public  SparseFieldMatrix(SparseFieldMatrix<T> other);
    public  SparseFieldMatrix(FieldMatrix<T> other);

}