need help using the rand function.

hey guys i have got Matlab2010a and i am trying to implement the code below but i can't seem to get it to work. when i run it in matlab, it comes up with an error saying: ??? Error using ==> randperm Too many input arguments.

fo=4 fs=100 ts=1/fs t=0:ts:1-ts n=length(t) y=2*sin(2*pi*fo*t) plot(t,y) numberOfSamplesToTake = 20; sampleIndexes = randperm(numel(y), numberOfSamplesToTake) % Plot the samples; ts = t(sampleIndexes) ys = y(sampleIndexes) hold on; plot(ts, ys, 'r*');

Answer 1

[Andrei Bobrov]

Use:

numberOfSamplesToTake = 20;
a = randperm(numel(y));
sampleIndexes = a(1:numberOfSamplesToTake);

[Kel]

worked perfectly. i have been struggling with that for a long time. thank you so much.

Answer 2

[Jos (10584)]

In recent versions of MatLab, randperm(N,M) randomises the numbers 1:N and takes the first M values. In older versions (like 2010a) you can mimic this functionality by replacing it with these two steps:

A = randperm(N) ; 
A = A(1:M) ;