How can I efficiently vectorize a for-loop in MATLAB? Provide an example where vectorization significantly improves performance compared to a traditional loop.

How can I efficiently vectorize a for-loop in MATLAB? Provide an example where vectorization significantly improves performance compared to a traditional loop.

[Dyuman Joshi]

MATLAB Answers Help Point #1 - Search, search and search

Answer 1

[recent works]

Example to calculate the cumulative sum of an array using a for-loop and its vectorized version:

% Sample array
arr = 1:100000;

% Using for-loop
tic;
sum_loop = 0;
for i = 1:length(arr)
    sum_loop = sum_loop + arr(i);
end
time_loop = toc;

% Using vectorization
tic;
sum_vectorized = sum(arr);
time_vectorized = toc;

disp("Using for-loop: Sum = " + sum_loop + ", Time taken = " + time_loop + " seconds.");
disp("Using vectorization: Sum = " + sum_vectorized + ", Time taken = " + time_vectorized + " seconds.");

[Les Beckham]

In case someone want to actually see the results:

% Sample array
arr = 1:100000;
% Using for-loop
tic;
sum_loop = 0;
for i = 1:length(arr)
    sum_loop = sum_loop + arr(i);
end
time_loop = toc;
% Using vectorization
tic;
sum_vectorized = sum(arr);
time_vectorized = toc;
disp("Using for-loop: Sum = " + sum_loop + ", Time taken = " + time_loop + " seconds.");

Using for-loop: Sum = 5000050000, Time taken = 0.019152 seconds.

disp("Using vectorization: Sum = " + sum_vectorized + ", Time taken = " + time_vectorized + " seconds.");

Using vectorization: Sum = 5000050000, Time taken = 0.001957 seconds.