use Math::Complex; my ( $m11, $m12) = ( 1 + i, 2 + i); my ( $m21, $m22) = ( 1 - 2*i, 2 - i); my $b1 = 5 + 10*i; my $b2 = 8 - 5*i; my $xsub1 = 3 + i; my $xsub2 = 2 + i; my $r1 = $m11*$xsub1 + $m12*$xsub2; my $r2 = $m21*$xsub1 + $m22*$xsub2; print "$r1 (should be $b1)\n"; print "$r2 (should be $b2)\n";