rand('seed',1)
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hi there, can anyone explain me the different between using 'rand('seed',1)' inside the loop and outside the loop? Assuming I generate some random number inside the loop.
Ta,Rak
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Accepted Answer
Jan
on 30 Nov 2011
Seeding the random number generator means initializing it to a certain status. Seeding inside the loop means, that all "random" numbers created inside the loop will be the same in each iteration:
for i = 1:3
rand('seed', 1);
disp(rand);
end
Result: 0.51291 0.51291 0.51291
This is not very useful. Seeding RAND outside the loop allows you to reproduce the results:
for j = 1:2
rand('seed', 1);
for i = 1:3
disp(rand);
end
end
Now you get two series of 3 different numbers:
0.51291 0.46048 0.3504 0.51291 0.46048 0.3504
3 Comments
Peter Perkins
on 1 Dec 2011
Unless you are using an extraordinarily old (from the early 1990's) version of MATLAB, you should not be using rand('seed',1) at all. It most likely does not do what you think it does. If you are using R2011a or newer, see this:
<http://www.mathworks.com/help/techdoc/math/bs1qb_i.html>
Otherwise, see the documentation in whatever version you are using.
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