How to optimize this code by avoiding nested for loops?

Hi all,

I have written the following code, whose Elapsed time is 32.427771 seconds.

t=1;
ObsX=[]; ObsY=[];

tic
for i = 3.53:0.0001:4.67
    for j = -6.17:0.0001:-4.53
        ObsX(t) = j;
        ObsY(t) = i;
        t=t+1;
    end 
end
toc

I have rectangular obstacle with the coordinates 3.53:4.67 and -6.17:-4.53 and the resolution is 0.0001. I am trying to store the X coordinates in array ObsX and Y coordinates in array ObsY.

Can you suggest way to improve the computation time? Thanks!

Answer 1

[Walter Roberson]

[X, Y] = ndgrid(3.53:0.0001:4.67, -6.17:0.0001:-4.53);
ObsX = X(:);
ObsY = Y(:);

Note: I did not check to be sure that the values are in the same order as you created. You might need meshgrid() instead of ndgrid()