which for loop will completed first ??

for i=1:5 
 for j=1:4 
v(i,j)=w*v(i,j)+c1*rand()*(pbest(i,j)-x(i,j))+c2*rand()*(gbest(1,j)-x(i,j)); 
 end 
end 

how this loops will work.

thanks in advance

[madhan ravi]

a=rand(3);
m=size(a,1);
n=size(a,2);
b=zeros(size(a,1),size(a,2));
for i=1:m
for j=1:n
b(i,j)=a(i,j)  % this will make you understand the working of nested for loops
end
end

[Stephen23]

"which for loop will completed first ??"

Of any nested loops, the innermost one will finish first.

Answer 1

[Image Analyst]

The inner j loop will finish first, for any given i. The j loop will execute its 4 iterations 5 times - one iteration of 4 times for every one of the 5 i values.

If the loops got very large (tens of thousands of iterations), you might notice a speed up if you switched the i and j loop because MATLAB is "column major" so it goes down rows (left most index) first before jumping over to the next column. So it would be faster if the inner most loop variable were the left most index.