rand('state',11)

Can anyone please explain this statement:

rand('state',11) ?!

[Hussein Adel]

no one since 2011 :)

[Steven Lord]

No one responded since February 1st, 2018. The answers given then and back in 2011 are still valid.

Answer 1

[Greg Heath]

rand is an obsolete random number generator that generates uniformly distributed outputs in the open interval (0,1).

rand(m,n) produces a matrix of size [m n] and rand(n) = rand(n,n)

Each time rand is called, the state of the generator is changed and a new sequence of random numbers is generated.

There are 2^1492 states, 2^32 of them are so-called integer states.

rand('state',N) for integer N in the closed interval [0 2^32-1] initializes the generator to the Nth integer state.

SEE THE DOCUMENTATION:

help rand

doc rand

Hope this helps.

Greg

[Steven Lord]

Greg, I have a slight issue with the way your first sentence is worded. The rand function is not obsolete; it is the recommended way to generate uniform random numbers.

The particular syntax for rand about which the poster asked, where you use it to control the internal state information about the pseudorandom number generators, is what is discouraged (though describing it as obsolete is close enough.) We recommend using the rng function instead.

Answer 2

[Wayne King]

did you read that document, it is explained there. It is a seed. The seed is an integer, you can use it to produce repeatable results.

rand('state',11)
rand(4,1)
% now seed back to where you were
rand('state',11)
rand(4,1)
% the same 4 numbers both times, now
rand('state',1)
rand(4,1)
% see they're different

Answer 3

[Wayne King]

rand('state',seed_number) is an old way of seeding the MATLAB v5 random number generator.

[habady]

in either cases i need to understand, what does it mean or refer to

Answer 4

[Steven Lord]

See this page in the documentation for an explanation of that syntax and the recommended replacement.

Answer 5

[yasmine Zem]

Bonjour j'ai un problème avec mon algorithme il veut pas marcher je voudrais avoir des explications svp clf

randn ('state',1)

T = 1; N = 2^8; Delta = T/N; lambda = 0.05; sigma 0.8; Xzero = 1;

Xem = zeros (1, N+1);

Xem (1) = Xzero;

for j = 1:N

Winc = sqrt (Delta) *randn;

Xem (j+1)=abs (Xem (j) + Delta*lambda*Xem (j) + sigma\sqrt(Xem (j)) *Winc);

end

plot ( [0:Delta:T],Xem, 'r--') xlabel ('t','FontSize', 16), ylabel ('X', 'FontSize', 16)