How do I fill a matrix with values of an one array based on another array?

Hi,

I have a 1x5001 array Rr which contains radial distances from a pointsource. I also have an 5001x 1 array Wzr which is the weight vs. radial distance. Also there is a constant dr.

Now I need to make a 2D matrix (5000 x 5000) which is Wzr2D(a,b) = Wzr (Rr(a,b)/dr)

For example if Rr(1,2) = 10 and dr = 2 then I need the value of Wzr(5) to be placed in the matrix Wzr2D at the position (1,2).

I am a super beginner at MATLAB and I don't ever know where to begin to link all this together.

[Adam Danz]

To begin, learn about indexing.

https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html

It shouldn't take much time to work through that page. Indexing is necessary to know if you're using Matlab and it's a very basic tool.

Answer 1

[TADA]

If I understood correctly, try this:

Wzr2D(1,:) = Wzr(Rr(1:5000) / dr)

This should work if you can guarantee that all values of Rr/dr are valid indices of Wzr, that is, integers between 1 and 5001

[TADA]

I'm not sure why you want to dispose the last element of your data though, nor what's the extra dimention of Wzr2D for