function specplot(P,Fs)
%SPECPLOT Plot the output of the SPECTRUM function.
%	SPECPLOT(P,Fs), uses P, the output of SPECTRUM, and Fs, the
%	sample frequency, to successively plot:
%
%		Pxx - X Power Spectral Density & confidence.
%		Pyy - Y Power Spectral Density & confidence.
%		abs(Txy) - Transfer Function Magnitude.
%		angle(Txy) - Transfer Function Phase.
%		Cxy - Coherence Function.
%
%	The 95% confidence intervals are displayed on the power
%	spectral density curves.
%
%	SPECPLOT(P) uses normalized frequency, Fs = 2, so that 1.0 on
%	the frequency axis is half the sample rate (the Nyquist 
%	frequency).

%	J.N. Little 7-9-86
%	Revised 11-14-91 JNL
%	Copyright (c) 1986-91 by the MathWorks, Inc.

[n,m] = size(P);
if nargin < 2
   Fs = 2;
end
f = (1:n-1)/n*Fs/2;

if m == 2
   c = [P(2:n,1)+P(2:n,2) P(2:n,1)-P(2:n,2)];
  else
   c = [P(2:n,1)+P(2:n,6) P(2:n,1)-P(2:n,6)];
end
c = c .* (c > 0);
semilogy(f,P(2:n,1),f,c(:,1),'--',f,c(:,2),'--'), ...
title('Pxx - X Power Spectral Density'), ...
xlabel('Frequency')
if m == 2
   return
end

pause

c = [P(2:n,2)+P(2:n,7) P(2:n,2)-P(2:n,7)];
c = c .* (c > 0);
semilogy(f,P(2:n,2),f,c(:,1),'--',f,c(:,2),'--'), ...
 title('Pyy - Y Power Spectral Density'), ...
 xlabel('Frequency'), pause

semilogy(f,abs(P(2:n,4))), ...
 title('Txy - Transfer function magnitude'), ...
 xlabel('Frequency'), pause

plot(f,180/pi*angle(P(2:n,4))), ...
 title('Txy - Transfer function phase'), ...
 xlabel('Frequency'), ...
 ylabel('Degrees'), pause

plot(f,abs(P(2:n,5))), ...
 title('Cxy - Coherence'), ...
 xlabel('Frequency'), pause

