MATLAB Programming

Techniques for Improving Performance
i = 0;
for t = 0:.01:10
i = i + 1;
y(i) = sin(t);
end
A vectorized version of the same code is
t = 0:.01:10;
y = sin(t);
The second example executes much faster than the first and is the way
MATLAB is meant to be used. Test this on your system by creating M-file
scripts that contain the code shown, and then using the tic and toc functions
to time the M-files.
Advanced Example of Vectorizing
repmat is an example of a function that takes advantage of vectorization. It
accepts three input arguments: an array A, a row dimension M, andacolumn
dimension N.
repmat creates an output array that contains the elements of array A,
replicated and “tiled” in an M-by-N arrangement:
A = [1 2 3; 4 5 6];
B = repmat(A,2,3);
B =
1 2 3 1 2 3 1 2 3
4 5 6 4 5 6 4 5 6
1 2 3 1 2 3 1 2 3
4 5 6 4 5 6 4 5 6
repmat uses vectorization to create the indices that place elements in the
output array:
function B = repmat(A, M, N)
% Step 1 Get row and column sizes
[m,n] = size(A);
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