Pick three numbers at random from a vector

How do you pick three numbers at random from a vector?

So I have a=1:10, a1=a(1:2:end) and I want to select three numbers at random from a1. I've tried a2=randperm(a1,3) but I get an error :

Error using randperm
Inputs must be nonnegative scalar integers.

Any help is greatly appreciated!!

[David Young]

So did you even look at the answer to your previous question, which included the use of randperm?

Answer 1

[Image Analyst]

Try this:

a=1:10;
a1=a(1:2:end) 
indexesToUse = randperm(numel(a1),3) % 3 random indexes
a2 = a1(indexesToUse)  % Extract 3 values from a1

[Alice]

Fab Thank you!!