%First find the maximum values
maxes(1)=max(p100(:));maxes(2)=max(p1k(:));maxes(3)=max(p100k(:));maxes(4)=max(p10M(:));
maxes=maxes(:).*1e6;
maxes=repmat(maxes,1,2);
%Now find the x-extent
x_range=[min(freq(:)) max(freq(:))];
%plot the curves
semilogy(freq,p100*1e6,'b',freq,p1k*1e6,'m',freq,p100k*1e6,'c',freq,p10M*1e6,'--')
legend('100\Omega','1k\Omega','100k\Omega', '10M\Omega')
xlabel('Excitation frequency (Hz)')
ylabel('|Power FRF| [\muW/g^2]')
%plot the limit lines (you could also use a loop for this)
hold on
plot(maxes,x_range)
