How do I create a random double generator where only multiples of .05 are used?

I am trying to randomly generate a double, however it needs to be within .25 and .7 and it has to be divisible by .05.

Answer 1

[Geoff Hayes]

Giann - you could create an array of all the numbers within the interval [0.25, 0.7] that are multiples of 0.5, and then just randomly pick one.

 % create an array of choices, where each is a multiple of 0.05
 choices = [25:5:70]/100.0;

 % randomly pick one using *randi*
 randomDbl = choices(randi([1 length(choices)],1,1));

If we take your original interval and multiply it by 100, then we get [25,70]. Then we can create the array of choices which is every integer from 25 to 70 using a step size of 5. When we divide the result by 100, we have all doubles within the interval [0.25,0.7] that are multiples of 0.05.

Now we use randi to randomly choose an index between 1 and the number of choices, length(choices), and use that index to pick our "random" double.

Try the above and see what happens!