Random number multiple of 5 generation

Hello everyone,

I want to generate a random number which is a multiple of 5 (number that finish either by 0 or 5) and which is bound in an interval: [interMin; interMax].

example:

interMin=20; % lower bound

interMax=150;% upper bound

I know that I can generate a random number as shown below:

NUMBER=randi([interMin interMax],1,1);

But I want this number "NUMBER" to be a multiple of 5.

Do you know how to do this ?

Thank you in advance.

Vincent

[AMJR21]

I'm over 3 years late but you could just make it generate a random number and multiply it by 5 after

Answer 1

[Daniel M]

First find out how many possibilities there are:

interMin = 20;
interMax = 150;
n = sum(~mod(interMin:interMax,5));
% n = 27
% or just, n = (interMax-interMin)/5 + 1;

That means there are 27 multiples of 5 from interMin to interMax.

Now pick a random one.

var = (randi(n)-1)*5 + interMin;

You can test that it works properly like this:

isequal((1-1)*5 + interMin, interMin) % ans = 1
isequal((n-1)*5 + interMin, interMax) % ans = 1

Here is a handy way to generate as many values as you want, using an anonymous function:

pickN = @(N) (randi(n,N,1)-1)*5 + interMin;
vals = pickN(10000); % vals is [10000x1]

% visually check if it works
figure
histogram(vals,n)
% all bins should be roughly equal