How do I update array elements through a loop?

How do I update an element in array. So I have an array of say 5 zeros:

[00000]

How do I change certain elements of the array one at a time.

What I mean is how do I go from the following:

[0 0 0 0 0 0]

[4 0 0 0 0 0]

[4 1 0 0 0 0]

[4 1 9 0 0 0]

[4 1 9 6 0 0]

[4 1 9 6 2 0]

[4 1 9 6 2 8]

[Sargondjani]

It is not so clear what you exactly want to do. But maybe this helps?

cross_corr = zeros(1,1999)

%Compute each element:

for ii = 1:size(cross_corr,2)

cross_corr(1,ii) = %your computation comes here

end

[Justin Saxon]

Sorry, I included way too much pointless information in the question.

How do I have an array of 5 zeros -----> [0 0 0 0 0]

and update the elements of the arrays one at a time.

So I go through a loop and end up with a variable. I want to plug that variable into element 1 of the array. Then the loop goes back through and the variable is something new and the new variable goes in element 2. This goes on 1999 times. I have the code I just don't know how to replace the zero with my variable. Its something very simple

Answer 1

[Steven Lord]

The empty Static method (you'd made a typo and used emtpy instead of empty) creates a 0-by-0 array of the class when called with no input arguments. When called with a size vector or multiple arguments it creates an array of that size (and at least one of the dimensions must be 0.)

Instead of creating a 0-by-0 empty and assigning to elements of it (growing it each time) I'd preallocate the matrix of the appropriate (non-empty) size and then assign to it. The zeros function will let you do this preallocation with each element of the result containing 0.

z = zeros(1, 5)

z = 1×5

0 0 0 0 0

z(3) = 42

z = 1×5

0 0 42 0 0

z(2) = -999

z = 1×5

0 -999 42 0 0

z(5) = NaN

z = 1×5

0 -999 42 0 NaN