about random again

1 view (last 30 days)
Niki on 12 Jun 2012
I have one matrix as follows X = rand(4,10)
I want to generate a matrix from X and in each row a variable should be randomly selected and all possible combination can be used. actually the following code works for a small set like d = rand(4,3) but i have problem when a larger set like above X = rand(4,10) used , please run this and let me know .
[m,n] = size(x);
df = bsxfun(@plus,fullfact(m*ones(1,n)),(0:n-1)*m);
k = randperm(size(df,1));
out = x(df(k(1:min(100,numel(k))),:));
Niki on 12 Jun 2012
actually when I generate my matrix like for example follows
X = rand(10,23)
then i get the size of my matrix
[m,n] = size(X);
then I do
df = bsxfun(@plus,fullfact(m*ones(1,n)),(0:n-1)*m);
I will get error as
??? Error using ==> zeros
Maximum variable size allowed by the program is exceeded.
Error in ==> fullfact at 33
design = zeros(ssize,cols,class(levels));

Sign in to comment.

Answers (1)

Walter Roberson
Walter Roberson on 12 Jun 2012
If I calculate correctly, fullfact(m*ones(1,n)) creates m^n rows of output each of width n.
When X = rand(10,23) then you are asking for 10^23 rows each of width 23, and each element takes 8 bytes (double precision), so you are asking for (8*23) * 10^23 bytes of output. That would be about 2^84 bytes. That exceeds the largest variable that can be handled on a 64 bit operating system (2^64 bytes).
  1 Comment
Niki on 12 Jun 2012
so what should I do to prevent such problem?
can you help me ?

Sign in to comment.


Find more on Operating on Diagonal Matrices in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!