Generate consistent pairwise matrix

I have created the following function which creates a pairwise matrix:

function P=pairwise_matrix(S,n)

P=zeros(n,n);

for i=1:n

for j=1:n

if (i==j)

P(i,i)=1; % fill in the diag

elseif j>i % fill in the upper triangular array

P(i,j)=S(ceil(length(S).*rand(1,1)));

end %eof if

end % eof for j

end %eof for i

%fill in the lower triangular array

for k=2:n

for m=1:(k-1)

P(k,m)=1/P(m,k); %otherwise P(k,m)=inv(P(m,k));

end %eof k

end %eof m

endfunction

In another function I calculate the consistency ration, in order to drop the tables that are not consistent. Is there any way of generating consistent matrices in the first place, so that I don't have to drop them later? Could for example the line P(i,j)=S(ceil(length(S).*rand(1,1))); be written different to achieve that?