how can i generate a random number out of a range??

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i need to generate a random number out of a range, i did it inside with r=-1+(2).*rand(1,1) %my interval is (-1;1)
how can i do to get a random number that is not in this interval?? i mean, a number which satisfy r<-1 U 1<r

Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 21 Jan 2014
Edited: Azzi Abdelmalek on 21 Jan 2014
a=rand
out=1/a*sign(a-0.5)
%or for a vector
n=10;
a=rand(1,n);out=1./a.*sign(a-0.5)
  2 Comments
Amit
Amit on 21 Jan 2014
Edited: Amit on 21 Jan 2014
I think this technique would be biased. The negative random number would be always bigger while the positive ones will always be smaller.
Azzi Abdelmalek
Azzi Abdelmalek on 21 Jan 2014
You are right, if we use rand twice, it will be different
n=10;
out=1./rand(1,n).*sign(rand(1,n)-0.5)

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More Answers (1)

Amit
Amit on 21 Jan 2014
A = [1/rand -1/rand];
r = A(randi(2));
(or)
r = [1/rand -1/rand]*(randperm(2,2) -1)';
Either will generate a random number from r<-1 U 1<r

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