I need to display the max value in this function.

I have been working on a script for a function 'collatz' and I originally made it way more complex than it needed to be. I've managed to simplify it down to this:

function [s,m]=collatz(num)

cnt=0;
m=-inf;
while num>1
    cnt=cnt+1;
    if mod(num,2);
        num=num*3+1;
    else
        num=num/2;
    end

      end

The only problem I have is getting 'm' to represent the maximum value. The 's' displays the number of steps it takes to complete the while loop. That part of the script works fine. Example of what I would need: >>[s,m]=collatz(3) %which would take 7 steps in my function with a max value of 16. s= 7 m= 16

[Stephen23]

See my answer for a simpler solution.

Answer 1

[KSSV]

function [s,m]=collatz(num)
cnt=0;
X = zeros([],1) ;

while num>1
    cnt=cnt+1;
    if mod(num,2)
        num=num*3+1;
        X(cnt) = num ;
    else
        num=num/2;
        X(cnt) = num ;
    end
end
m = max(X) ;
fprintf('Maximum values is:%f\n',m)

[Kevin Smith]

Thanks for your help!

Answer 2

[Stephen23]

Rather than enlarging the array on each iteration as KSSV showed (and in general is a bad practice that should be avoided), you should simply call max on each iteration, which makes the code simpler too:

function [cnt,mxv] = collatz(num)
cnt = 0;
mxv = 0;
while num>1
    cnt = cnt+1;
    if mod(num,2) % odd
        num = num*3+1;
    else % even
        num = num/2;
    end
    mxv = max(mxv,num);
end
end

And tested:

>> [s,m] = collatz(3)
s =
     7
m =
    16