$MAX  = 1024;   ##  the largest random value, and the length of
                    ##  our RNG's period.   you can use any power
                    ##  of two if you want a larger (or smaller) 
                    ##  period.

    $A    = 5;      ##  $A should be relatively prime to $MAX, and
                    ##  ($A-1) should be divisible by 4 if $MAX is
                    ##  divisible by 4 (it is).

    $C    = 113;    ##  $C must be relatively prime to $MAX, and 
                    ##  113 is prime, full stop.
    
    $SEED = 42;     ##  just a starting value, and all good
                    ##  _Hitchhiker's Guide_ fans love 42.

    sub lcrng {
        if ( ! defined $CURRENT ) {
            $CURRENT = $SEED;
        }
        $CURRENT = (($CURRENT * $A) + $C) % $MAX;
        return ($CURRENT / $MAX);
    }
    
    ##  and some test code
    
    for $i (1..1032) {
        printf "%5.3f ", lcrng();
        print "\n" if (0 == $i % 8);
    }