MATLAB: Is the “state” important

random number generator

I am going through a code which uses 'state' in a line. What does 'state' do, and could it be of importance? I read that it "resets the generator to its 100th state", but what does this mean?

rand('state',100)

Best Answer

Start reading here: New Ways With Random Numbers, Part I.

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MATLAB: How to fix the seed in the trnd function

I'm not sure why you want to do that since you can use rng() without using the legacy mode by removing those calls and using rng() instead.

But if you are insisting, then you have to do something like:

rng(sd,'v5uniform')

for calls to rand()

and

rng(sd,'v5normal')

for randn(), where sd is the seed.

You should enter

>>help rng

at the command line and read the documentation linked from

Updating Your Random Number Generator Syntax.

This is all explained there in detail.

MATLAB: What 0 represents in rand function

See this link http://www.mathworks.com/help/matlab/math/updating-your-random-number-generator-syntax.html which discusses the "discouraged" syntaxes of rand, which includes your example of rand('state',0).

From the documentation:

In earlier versions of MATLAB®, you controlled the random number generator used by the rand and randn functions with the 'seed', 'state' or 'twister' inputs...These syntaxes referred to different types of generators, and they will be removed in a future release for the following reasons:

The terms 'seed' and 'state' are misleading names for the generators.
All of the former generators except 'twister' are flawed.
They unnecessarily use different generators for rand and randn.

It goes on to discuss what the intent was behind rand('state',sd), why it was discouraged, and what it should be replaced by.

In your case, the alternative for rand('state',sd) would be rng(sd). It is best to use the recommended alternative as per the note.

You can verify that the original call still does work (though it should be replaced!). In the Command Window type

 rand('state',0)
 A = rand(100,1);
 rand('state',0);
 B = rand(100,1);
 find((A-B)~=0)

Note that A and B will have the same set of randomly generated numbers, so find((A-B)~=0) will be zero.

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MATLAB: How to fix the seed in the trnd function

MATLAB: What 0 represents in rand function

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