how can I find the rows number that all are zero?

I have a matrix for example:

prec=[ 0 0 0 0; 0 0 0 0; 1 0 0 1; 0 1 0 1];

I want to find the rows number that all the elements are zero i.e. first and second row. I write my cod as:

for i=1:4;

x=find(prec(i,:))==0

end

but it gives wrong answer. How can I write it?

Thanks in advance...

Answer 1

[Guillaume]

find(all(prec == 0, 2))

No need for a loop. Use all.

[John D'Errico]

Or even this...

find(all(~prec,2))

Answer 2

[bilgesu ak]

Thanks very much, it works!