ActionScript for Flash MX: The Definitive Guide, Second Edition

Math.round() Method

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ActionScript Language Reference

// Note that to simulate two dice, you can use this:

twoDice = myRandom(2, 12); // The minimum value is 2, not 1

// To return the die values separately, use an array

function rollTwoDice () {

return [myRandom(1, 6), myRandom(1, 6)];

}

Due to a bug in Flash Player 5.0.30.0, this approach is prone to an extremely rare, but

potentially important inaccuracy. In Flash Player 5.0.30.0, random( ) generates values in the

range of 0.0 to 1.0, inclusive. When we multiply the return of random( ) by an integer, n,

we produce values in the range of 0.0 to n. In our example, we multiplied Math.random( )

by 6, so that the returned value ranges from 0.0 to 6.0. By invoking floor( ) on the adjusted

value, we produce integers in the range of 0 to n (0 to 6 in our example). The scaling and

rounding leads to an inaccurate distribution of random numbers—the chance of producing

n is much smaller than the chance of producing any other number in the series.

The Math.random( ) was fixed in Flash Player 5.0.41.0. If supporting older versions of the

Player, the following version of the myRandom( ) function avoids the problem by simply

discarding the value 1.0 if it happens to be chosen by Math.random( ):

// Returns an integer in the range of minVal to maxVal ...