# How can I create a nested loop ?

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Samantha Cepeda on 9 Apr 2018
Commented: Wiqas Ahmad on 18 Mar 2021
Please, I'm trying to solve this problem: Create two “for loops”, one for i running from 1 to 5 by 1 and the other nested inside the first for j running from 1 to 8 by 1. Inside the nested loop, calculate the sum of the current I and j values and output the sum to the user followed by a tab.
I tried and did this:
clear, clc
i=0; j=0;
for i = 1:1:5 for j = 1:1:8
sum(i,j) = i + j;
end
end
fprintf ( '%g \t', sum)
I want to see if I did it right, I'm still confused on "sum" value. Thank you
##### 3 CommentsShow 1 older commentHide 1 older comment
Samantha Cepeda on 9 Apr 2018
Edited: Samantha Cepeda on 9 Apr 2018
clear, clc
for i = 1:5
for j = 1:8
b(i,j) = i + j;
end
end
fprintf ( '%g \t', sum)
yes, it is a homework. I took C++ like two years ago and I'm using Matlab now. I'm a little bit lost and worried. Thank you for your help. I didn't quite understand when you referred to 'You should initialize an array (e.g. with the zeros function) before the loop.' What's the zeros function? I've seen people using j=0 or i=0 at the beginning, is that a case when I need to initialize a variable or not at all?
Wiqas Ahmad on 18 Mar 2021
How to write b if there are three loops indices, i.e i,j,k?

Von Duesenberg on 9 Apr 2018
Here is a possible solution ; adapt it if it doesn't quite do what you had in mind :
iMax = 5;
jMax = 8;
myArray = zeros(iMax, jMax);
for iIdx = 1:iMax
for jIdx = 1:jMax
myArray(iIdx,jIdx) = iIdx + jIdx;
end
end
Samantha Cepeda on 10 Apr 2018
Thank you so much!

muhammad mazhar on 7 Oct 2019
if we have double sigma used for nested loop with energy formula how coulid we implment in matalab like we have an equation