function freqhist(bb,nf)
zz=size(bb);
sr=750000/76;
freq=(nf-1)*sr/2/(zz(2)-1);
nframes=zz(1)*(zz(2)-1)/25000;
%
% plot absolute value histogram
%
subplot(3,1,1)
hist(log10(abs(bb(:,nf))),50)
xlabel('log_{10} (absolute value fft)')
ylabel('number of samples')
title(['Histograms at ',sprintf('%8.2f',freq),' Hz  from ',num2str(nframes),'  frames'])
%
% real part of fft
%
[nn xx]=hist(real(bb(:,nf)),50);
mur=mean(real(bb(:,nf)));
sdr=std(real(bb(:,nf)));
ny=gausshist(mur,sdr,zz(1),xx);
subplot(3,1,2)
%doublehist(xx,nn,ny)
hist(real(bb(:,nf)),50)
xlabel('real part fft')
ylabel('number of samples')
%
x1=(3*xx(1)-xx(2))/2;
x2=.9*max([nn,ny]);
x3=(8*xx(end)+xx(1))/9;
x4=.8*max([nn,ny]);
text(x1,x2,'red = data')
text(x1,x4,'blue = Gaussian fit')
text(x3,x2,['\mu = ',sprintf('%6.2f',mur)])
text(x3,x4,['\sigma = ',sprintf('%6.2f',sdr)])
%
% imaginary part of fft
%
[nn xx]=hist(imag(bb(:,nf)),50);
mui=mean(imag(bb(:,nf)));
sdi=std(imag(bb(:,nf)));
ny=gausshist(mui,sdi,zz(1),xx);
subplot(3,1,3)
doublehist(xx,nn,ny)
%hist(imag(bb(:,nf)),10)
xlabel('imaginary part fft')
ylabel('number of samples')
x1=(3*xx(1)-xx(2))/2;
x2=.9*max([nn,ny]);
x3=(8*xx(end)+xx(1))/9;
x4=.8*max([nn,ny]);
text(x1,x2,'red = data')
text(x1,x4,'blue = Gaussian fit')
text(x3,x2,['\mu = ',sprintf('%6.2f',mui)])
text(x3,x4,['\sigma = ',sprintf('%6.2f',sdi)])