Storing a variable outside of a loop

[cvxdes]

We're trying to work on our acceleration algorithm. At first we were going to go with the accelerometer, but the thing is actually a lot more unpredictable than we thought, so we now want to use just a straight line for acceleration, something like y=mx+b. Only problem is, we can't seem to figure out how to store the previous y, since y will become b the next time around the loop. I know how to do this in php, but I have NO idea about LabVIEW.

Since what I just said could be kinda confusing, here's how I would have coded it if robots could run php:

PHP Code:

<?
$override = false; // This would become true if the pilot presses a button, for taking turns or suddenly going in reverse to brake. 
$current_speed = 0;
$wants_to_go = 1;
$acceleration = 0.05;
while(true){
    if(!$override){
        while($current_speed <= $wants_to_go){
            $current_speed = $current_speed + $acceleration;
        }
    }else{
        $current_speed = $wants_to_go;
    }
}
?>