use  Math::MatrixReal;
$a = Math::MatrixReal->new_from_rows( [[1, 2], [3, 4]] );
$b = Math::MatrixReal->new_from_cols( [ [1, 1] ] );
print $a*$b;
# print "[  3.000000000000E+000 ]
#        [  7.000000000000E+000 ]"