summing logicals i times where i is taken from a matrix of integers

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J T
J T 2016-9-9
编辑： Andrei Bobrov 2016-9-9
I have a matrix of integers R
and some sort of critical value
crit = 0.395
depending on the value of any integer (i) in this matrix I want to generate a second random identically sized matrix of integers containing the sum of i components of the logical
crit >= rand
that is, if i = 0, it would return 0
if i = 1, crit >= rand, it would return either 0 or 1
if i = 2, it would sum crit >= rand + crit >= rand and would return either 0,1 or 2
Thus if R is
R = [1 2 1; 2 3 0; 0 1 0]
it might return
[1 1 0; 2 2 0; 0 0 0]
or
[0 2 1; 1 1 0; 0 1 0]
etc
In reality R is large so I have to avoid loops.
Any help appreciated!

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采纳的回答

Andrei Bobrov
Andrei Bobrov 2016-9-9
编辑：Andrei Bobrov 2016-9-9
EDIT
crit = 0.395;
z = max(R(:));
n0 = numel(R);
s = size(R);
Lo = crit >= rand([s,z]);
ii = reshape(1:n0,s);
out = arrayfun(@(jj)sum(Lo(jj+(0:R(jj)-1)*n0)),ii);
or just
out = arrayfun(@(ii)sum(rand(ii,1) <= crit),R)
  2 个评论
J T
J T 2016-9-9
Thanks for the reply and answer but it doesn't seem to address the randomisation I require from the expression
crit >= rand
which would need to be generated i times and then summed with i being the value of the integer for that particular element of the matrix.

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更多回答（1 个）

J T
J T 2016-9-9
I think that's probably genius and I'll test it to make sure I get the right exponential recoveries in my Monte Carlo simulation
Many thanks!

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