how can i use several loops

Hi,

Can anyone explain to me how matlab read this loops

for k=1:nt-1

for i=1:nx

end (for i)

for i=nx:1

end (for i=nx:1)

end (for k)

- For example for k=1, matlab will start by i=1:nx (first loop for i)or it will pass to i=1 only.after, it will pass to i=nx (second loop) ?

Answer 1

[James Tursa]

MATLAB will do all of the loops in the order it encounters them. So for the k=1 iteration it will do the i=1:nx loop in its entirety and then do the i=nx:1 loop in its entirety. Then it will do the k=2 iteration and do both inner loops in their entirety again. For every iteration of k, both inner loops will be done in their entirety.

Side Note: If nx>1, that i=nx:1 loop won't do anything. Maybe i=nx:-1:1 was meant?

Answer 2

[gonzalo Mier]

I will try to explain as best as I can. To do that, I will give values to the variables. nt = 4, nx = 5:

for k=1:3 ( = [1,2,3])     
    k is executed 3 times
    disp(" k = "+k);
    for i=1:5 ( = [1,2,3,4,5])   
        i is executed 5 times for each k (3*5 = 15 times)
        disp(" i = "+i);
    end
    for j=5:1 ( = [])
        Not executed as 5:1 is an empty vector.
        To do it in the inverse way, you should write 5:-1:1
        disp(" j = "+j);
    end
end 

So the output in the screen is:

k = 1
i = 1
i = 2
...
i = 5
k = 2
i = 1
i = 2
...
i = 5
k = 2
i = 1
i = 2
...
i = 5

Answer 3

[m m]

How can i do only the first iteration in the first loop, then pass to second loop and do the first iteration. is it possible?