for loop grabs last element of array

Hi , I am working on a basic for loop example that I am going to apply to a more complex problem but I am running accross an issue. my for loop grabs the last element of my array

here is my basic code

N = [ 4 6 8 10];
M = N; 

T = 2; 

for k = 1 : length(M)
    x = linspace(-20,20, M(k));
    dt = T/N(k);
    y = sin(x) + M(k);
    yi = cos(x) + dt;
end
grid on
%plot (x, y, '-.', x,yi,'--')

result >> N

N =

Columns 1 through 3

     4     6     8

Column 4

    10

>> M(k)

ans =

    10

My question is ....why is it that I am seeing the last value in the array instead of the first value. when I type M(k), shouldn't I see 4 instead of 10. I am going to be running some calculations that will be grabbing each value of the array in order and using it from 4 to 10 but this gives me the impression that it works backward and I can see how this is going to give me futre errors

Can anyone enlighten me on this? Thank You

[Stephen23]

"why is it that I am seeing the last value in the array instead of the first value."

Because that is what you wrote your code to do.

"when I type M(k), shouldn't I see 4 instead of 10."

Yes, but only on the first loop iteration. After the last loop iteration k will be 4 and of course M(4) is 10.

Answer 1

[Ameer Hamza]

You are getting last value because you are writing this line after the loop is complete. At the end of the loop, the value of k is 4, hence it is showing the 4th element of M. Inside the for-loop, it will give each value one by one in order. In order to understand this, run your loop with the following change

for k = 1 : length(M)
  disp(M(k));  % <----- show the value of 'M(k)' during each iteration
  x = linspace(-20,20, M(k));
  dt = T/N(k);
  y = sin(x) + M(k);
  yi = cos(x) + dt;
end