$x = '1e-3'; 
$y = 0.001; 
if ( $x eq $y ) { print "$x and $y are equal.\n" }
else { print "$x and $y are not equal" }

print "\n";

$x = $x + 0;
if ( $x eq $y ) { print "$x and $y are equal.\n" }
else { print "$x and $y are not equal" }


##</code><code>##

1e-3 and 0.001 are not equal
0.001 and 0.001 are equal.