Random floating point double in Inclusive Range

Question

We can easily get random floating point numbers within a desired range [X,Y) (note that X is inclusive and Y is exclusive) with the function listed below since

Answer 1

My solution to this problem has always been to use the following in place of your upper bound.

Math.nextAfter(upperBound,upperBound+1)

or

upperBound + Double.MIN_VALUE

So your code would look like this:

double myRandomNum = Math.random() * Math.nextAfter(upperBound,upperBound+1) + lowerBound;

or

double myRandomNum = Math.random() * (upperBound + Double.MIN_VALUE) + lowerBound;

This simply increments your upper bound by the smallest double (Double.MIN_VALUE) so that your upper bound will be included as a possibility in the random calculation.

This is a good way to go about it because it does not skew the probabilities in favor of any one number.

The only case this wouldn't work is where your upper bound is equal to Double.MAX_VALUE