rand('state',11)
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habady
le 7 Oct 2011
Réponse apportée : yasmine Zem
le 26 Jan 2021
Can anyone please explain this statement:
rand('state',11) ?!
2 commentaires
Steven Lord
le 29 Mai 2020
No one responded since February 1st, 2018. The answers given then and back in 2011 are still valid.
Réponse acceptée
Greg Heath
le 7 Oct 2011
Modifié(e) : Greg Heath
le 1 Fév 2018
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
1 commentaire
Steven Lord
le 1 Fév 2018
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.
Plus de réponses (4)
Wayne King
le 7 Oct 2011
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
0 commentaires
Wayne King
le 7 Oct 2011
Modifié(e) : John Kelly
le 27 Mai 2014
rand('state',seed_number) is an old way of seeding the MATLAB v5 random number generator.
Steven Lord
le 1 Fév 2018
See this page in the documentation for an explanation of that syntax and the recommended replacement.
0 commentaires
yasmine Zem
le 26 Jan 2021
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)
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