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I am trying to estimate a 3-parameter weibul distribution with random numbers. But I dont understand the difference between rng('shuffle') and NO rng('shuffle'), I mean deleting the line. Both lines estimates random numbers in my code. Can someone tell me the difference?

And if you can give me any advice for my code for estimating a 3-parameter weibul estimation, I would appreciate that.

clear all

n = 1000;

t0 = 0.5;

b_A = 1:5;

T_A = 1:5;

LowerBound= [0 0 0];

rng('shuffle');

data = zeros(n,length(b_A),length(T_A));

params = zeros(length(b_A),length(T_A));

data2P = zeros(n,length(b_A),length(T_A));

params2p = zeros(length(b_A),4,length(T_A));

for k= T_A

for i= b_A

data(:,i,k) = wblrnd(i,k, [n,1]) + t0;

data2P(:,i,k) = wblrnd(b_A(i),T_A(k), [n,1]);

start = [i k t0];

custompdf = @(x,a,b,c) (x>c).*(b/a).*(((x-c)/a).^(b-1)).*exp(-((x-c)/a).^b);

opt = statset('MaxIter',1e5,'MaxFunEvals',1e5,'FunValCheck','off');

params(i,1:3,k) = mle(data(:,i,k),'pdf',custompdf,'start',start,'Options',opt,'LowerBound',LowerBound,'UpperBound',[Inf Inf min(data(:,i,k))])

params(i,4,k) = i;

params(i,5,k) = k;

params(i,6,k) = t0;

params2p(i,1:2,k) = wblfit(data2P(:,i,k));

params2p(i,3,k) = i;

params2p(i,4,k) = k;

end

end

the cyclist
on 21 Jun 2020

If you start a fresh instance of MATLAB, and generate a sequence of pseudorandom numbers, it will always be the same sequence. (Try it!)

If you do not use the

rng('shuffle')

then you will get the numbers from that sequence. If you do use it, then instead of traveling along that predetermined sequence of numbers, you will leap to a different point on that sequence, based on the time when you make the call to the function.

the cyclist
on 21 Jun 2020

Sorry, I did not mean to make you feel bad.

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"Initializes generator based on the current time, resulting in a different sequence of random numbers after each call to rng."

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