How to fix my function script?

this is edited my script:

function[s,m]=collatz()
%This function will show the steps and maxvalue of even and odd natural
%numbers. It will show the number of steps needed for the number num to
%reach 1. It will show the maxvalue in the list 
%Even numbers will be divided by 2
%Odd numbers will be multiplied by 3 and add to by one
%Both will run as long as the result is greater than 1
clc
s=0
m=?
while x>1
    if mod(x,2)==0 %shows x(natural number is even)
        x=x/2
    elseif mod(x,2)==1 %shows x(natural number is odd)
        x=x*3+1
    end

end
s=s+1;
m=max(?)?

The script above is what I understood from my professor's comments, but I am still lost the m(maxvalue) and what he is saying about my x value. Sorry if the picture is blurry or sideways.

Answer 1

[James Tursa]

You need to have the step increment and the max calculation inside your while loop.

m = x;  <-- Use this to initialize up front prior to the while loop

s = s + 1;  <-- Put this inside your while loop
m = max(m,x);  <-- Put this inside your while loop after the "if" block

[James Tursa]

Please post the entire error message you are getting. Is your code in a file called collatz.m? And that is the only stuff in the file?

You need to delete those last s=s+1 and m=max(m,x) lines, and move that m=max(m,x) line inside the while loop after the if-block.

[michael story]

function[s,m]=collatz(n)
%This function will show the steps and maxvalue of even and odd natural
%numbers. It will show the number of steps needed for the number num to
%reach 1. It will show the maxvalue in the list
%Even numbers will be divided by 2
%Odd numbers will be multiplied by 3 and add to by one
%Both will run as long as the result is greater than 1
s=0;
m=n;
while n>1
    s=s+1;
    if mod(n,2)==0 %shows x(natural number is even)
        n=n/2;
        m=max(m,n);
    else %shows x(natural number is odd)
        n=n*3+1;
        m=max(m,n);
    end
end

error message: >> collatz(n) Undefined function or variable 'n'.

[James Tursa]

My guess is you pushed the green triangle button in the editor to run this function. That will run the code without defining the input n. You need to call this from the command line like this:

n = 5;  % or whatever
[s,m] = collatz(n)

[michael story]

That was the mistake. Thank you!