Manipulate matrix of reals

Implements the data type "matrix of reals" (and consequently also
"vector of reals") which can be used almost like any other basic
Perl type thanks to OPERATOR OVERLOADING, i.e.,

$A = $matrix1 * $matrix2;
$B = $A ** 2;
$C = $A + 2*B;
$D = $C - $B/2;
$inverse = $C ** -1;
$inverse = 1/$C;

does what you would like it to do.