how to generate random integers without using built-in functions?

Hello,

I'm kind of stuck on this question and I'd appreciate the help.

Write a function permutation that will receive a positive integer n as an input argument. The function will return a vector of size n , where the elements of the vector are the positive integers from 1 to n , in random order. Each number from 1 to n should appear only once. You are required to use the programming method (loops, conditional statements). You are NOT allowed to use the following built-in Matlab functions: perms, randperm, randsample .

My code uses randperm and I don't know how I can write a code without using this builtin function.

Code:

function vec = permutation(n) vec = 1:n; index = 1:n; while any(vec == index); vec = vec(randperm(n)); end

end

Answer 1

[Adam]

doc rand
doc randi

Neither of these are on the list of functions you are not allowed to use and either one of them can be worked into an algorithm to achieve what you are being asked for.

[Sarah Sadeq]

thanks!

Answer 2

[Walter Roberson]

Hint: read the randperm source code