Nested for loops and saving data in a vector

Hello there,

I have a function that depends on two variables and I want to iterate through both variables and get the end result as a vector.

what I achieved so far is iterating through the variable r=1:7 (the seven entries in the vector "alpha") and getting a vector lambda(r) with seven entries.

That looks like this:

alpha=[-0.17445,0.09672,0.36789,0.63906,0.91023,1.1814,1.45257];
for r=1:7
    lambda(r)=10^(alpha(r)-log(L));
end

For testing purposes I just put L=10 above the code and it works, but I need to do this for L=1:100 so that I have at the end 100 sets of those seven values and I don't know how to save the seven r variables for each L after each step, let alone how to tell matlab to increase L after seven iterations. I could do the for loop 100 times and change the value manually, but that is obviously not suitable.

I tried nested for loops, but I can't get it to work.

Help would be greatly appreciated.

Answer 1

[Luna]

Hi,

First start with preallocation. lambda will be your 100x7 matrix, each row is a set of 7 calculation.

alpha=[-0.17445,0.09672,0.36789,0.63906,0.91023,1.1814,1.45257];
L = 1:100;

lambda = nan(numel(L),numel(alpha)); % preallocation
for k = 1:numel(L)
    for r = 1:numel(alpha)    
        lambda(k,r) = 10^(alpha(r) - log(L(k)));        
    end
end

[xXTacitusXx]

Awesome, it worked, thank you very much!

[Luna]

Your welcome :)