function rms=plotspectrumRMS(freq,varargin);
% plot cumulative RMS for many spectrums
% returns RMS

spe=[varargin{:}];
Nspe=size(spe,1);
Nfreq=length(freq);
cumulativeRMS=[];
for j=1:Nspe
    data=spe(j,:);
    cumulativeRMSsquared=zeros(1,Nfreq);
	for k=(Nfreq-1):-1:1
		cumulativeRMSsquared(k)=cumulativeRMSsquared(k+1)+(data(k+1)^2+data(k)^2)*(freq(k+1)-freq(k))/2;
    end
	cumulativeRMS=[cumulativeRMS;sqrt(cumulativeRMSsquared)];
end

rms=cumulativeRMS(:,1);

loglog(freq,spe,freq,cumulativeRMS,'--');
grid on;
xlabel('Frequency [Hz]');
ylabel('RMS [?]');