Generating arrays of random numbers without loop in MATLAB

Question

I have a loop which generates random samples from the chi-square distribution with different degrees of freedom (df1, df2, df3, df4) and saves it to a cell array:

for k=1:N
x{k} = chi2rnd([df1 df2 df3 df4]);
end

Is there any way to do this without any iterations? I tried to use cellfun, but it didn't work.

rahnema1 · Accepted Answer · 2020-09-19 15:11:28Z

2

Here is a vectorized way (method 1):

x = num2cell(chi2rnd(repmat([df1 df2 df3 df4], N, 1), N, 4), 2);

You may also try this method (method 2):

df = [df1 df2 df3 df4];
y = zeros(N,numel(df));
for k = 1:numel(df)
  y(:,k) = chi2rnd(df(k),N,1);
end
x = num2cell (y,2);

Result of timing for N = 10000 in Octave. However you need to measure the time in MATLAB:

Original solution :              3.91095 seconds
Vectorized solution (method 1):  0.0691321 seconds
Loop solution (method 2) :       0.0124869 seconds

answered Sep 19, 2020 at 15:11

rahnema1

15.9k3 gold badges17 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Generating arrays of random numbers without loop in MATLAB

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related