Plotting for loop with two outputs

I need to plot a function with a two variable output using any method. The graph should plot an x range of 2-1000000. I have used a for loop which should plot the prewritten function L, which outputs two different variables. Both are below.

%%This is the function that works. It is for the collatz conjecture. 
function [N, mx] = prob3_6(x)
X=x;%to initialise an X value that is not the input
N=0; %to initialise an N value that starts with 0 iterations.
mx=x; %create a definition for max in terms of x.
while X~=1; %while x is not 1, ends when x=1 if ever
    if mod(X,2); % if x is odd
        X=1+3*X; % do calculation for odd input
    else 
        X=X./2; %even numbers divided by 2
    end
    N=N+1 %for each loop, N will add 1 iteration from zero
    if X>mx; % if an X value happens to be greater than the set max, which is the input,
        mx=X %it will override that value with the new max.
    end
end

%% This is the code that does not work for plotting the function
for X=  2:1000000;
L=HW32P12Function(X);
end
figure(1)
loglog(X,L)
grid on

How do I use a this loop to plot the function that I have made?

[LO]

isn't there a typo there ? HW32P12 ?

also as you plot you want either to use "cla" after "figure(1)" to refresh the plotting or use hold on to keep all plots. Or what would you like to do ?

Answer 1

[KSSV]

X=  2:1000000;
n = length(X) ; 
L = zeros(1,n) ; 
for i = 1:n
    L(i) =HW32P12Function(X(i));
end
figure(1)
loglog(X,L)
grid on

[Petch Anuwutthinawin]

I have tried this but L is not indexed at the end, is there a way to do that so it can plot?

[KSSV]

Edited the answer.