


Multi-taper time-frequency coherence,cross-spectrum and individual spectra - continuous processes
Usage:
[C,phi,S12,S1,S2,t,f,confC,phistd,Cerr]=cohgramc(data1,data2,movingwin,params)
Input:
Note units have to be consistent. Thus, if movingwin is in seconds, Fs
has to be in Hz. see chronux.m for more information.
data1 (in form samples x trials) -- required
data2 (in form samples x trials) -- required
movingwin (in the form [window winstep] -- required
params: structure with fields tapers, pad, Fs, fpass, err, trialave
- optional
tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not
specified, use [NW K]=[3 5]
pad (padding factor for the FFT) - optional (can take values -1,0,1,2...).
-1 corresponds to no padding, 0 corresponds to padding
to the next highest power of 2 etc.
e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
to 512 points, if pad=1, we pad to 1024 points etc.
Defaults to 0.
Fs (sampling frequency) - optional. Default 1.
fpass (frequency band to be used in the calculation in the form
[fmin fmax])- optional.
Default all frequencies between 0 and Fs/2
err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
[0 p] or 0 - no error bars) - optional. Default 0.
trialave (average over trials when 1, don't average when 0) - optional. Default 0
Output:
C (magnitude of coherency time x frequencies x trials for trialave=0; time x frequency for trialave=1)
phi (phase of coherency time x frequencies x trials for no trial averaging; time x frequency for trialave=1)
S12 (cross spectrum - time x frequencies x trials for no trial averaging; time x frequency for trialave=1)
S1 (spectrum 1 - time x frequencies x trials for no trial averaging; time x frequency for trialave=1)
S2 (spectrum 2 - time x frequencies x trials for no trial averaging; time x frequency for trialave=1)
t (time)
f (frequencies)
confC (confidence level for C at 1-p %) - only for err(1)>=1
phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi - Note that
phi + 2 phistd and phi - 2 phistd will give 95% confidence
bands for phi - only for err(1)>=1
Cerr (Jackknife error bars for C - use only for Jackknife - err(1)=2)

0001 function [C,phi,S12,S1,S2,t,f,confC,phistd,Cerr]=cohgramc(data1,data2,movingwin,params) 0002 % Multi-taper time-frequency coherence,cross-spectrum and individual spectra - continuous processes 0003 % 0004 % Usage: 0005 % 0006 % [C,phi,S12,S1,S2,t,f,confC,phistd,Cerr]=cohgramc(data1,data2,movingwin,params) 0007 % Input: 0008 % Note units have to be consistent. Thus, if movingwin is in seconds, Fs 0009 % has to be in Hz. see chronux.m for more information. 0010 % 0011 % data1 (in form samples x trials) -- required 0012 % data2 (in form samples x trials) -- required 0013 % movingwin (in the form [window winstep] -- required 0014 % params: structure with fields tapers, pad, Fs, fpass, err, trialave 0015 % - optional 0016 % tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not 0017 % specified, use [NW K]=[3 5] 0018 % pad (padding factor for the FFT) - optional (can take values -1,0,1,2...). 0019 % -1 corresponds to no padding, 0 corresponds to padding 0020 % to the next highest power of 2 etc. 0021 % e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT 0022 % to 512 points, if pad=1, we pad to 1024 points etc. 0023 % Defaults to 0. 0024 % Fs (sampling frequency) - optional. Default 1. 0025 % fpass (frequency band to be used in the calculation in the form 0026 % [fmin fmax])- optional. 0027 % Default all frequencies between 0 and Fs/2 0028 % err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars 0029 % [0 p] or 0 - no error bars) - optional. Default 0. 0030 % trialave (average over trials when 1, don't average when 0) - optional. Default 0 0031 % Output: 0032 % C (magnitude of coherency time x frequencies x trials for trialave=0; time x frequency for trialave=1) 0033 % phi (phase of coherency time x frequencies x trials for no trial averaging; time x frequency for trialave=1) 0034 % S12 (cross spectrum - time x frequencies x trials for no trial averaging; time x frequency for trialave=1) 0035 % S1 (spectrum 1 - time x frequencies x trials for no trial averaging; time x frequency for trialave=1) 0036 % S2 (spectrum 2 - time x frequencies x trials for no trial averaging; time x frequency for trialave=1) 0037 % t (time) 0038 % f (frequencies) 0039 % confC (confidence level for C at 1-p %) - only for err(1)>=1 0040 % phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi - Note that 0041 % phi + 2 phistd and phi - 2 phistd will give 95% confidence 0042 % bands for phi - only for err(1)>=1 0043 % Cerr (Jackknife error bars for C - use only for Jackknife - err(1)=2) 0044 0045 if nargin < 3; error('Need data1 and data2 and window parameters'); end; 0046 if nargin < 4; params=[];end; 0047 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0048 0049 if nargout > 9 && err(1)~=2; 0050 error('Cerr computed only for Jackknife. Correct inputs and run again'); 0051 end; 0052 if nargout >= 7 && err(1)==0; 0053 % Errors computed only if err(1) is nonzero. Need to change params and run again. 0054 error('When errors are desired, err(1) has to be non-zero.'); 0055 end; 0056 [N,Ch]=check_consistency(data1,data2); 0057 0058 Nwin=round(Fs*movingwin(1)); % number of samples in window 0059 Nstep=round(movingwin(2)*Fs); % number of samples to step through 0060 nfft=max(2^(nextpow2(Nwin)+pad),Nwin); 0061 f=getfgrid(Fs,nfft,fpass); 0062 Nf=length(f); 0063 params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers 0064 0065 winstart=1:Nstep:N-Nwin+1; 0066 nw=length(winstart); 0067 if trialave; 0068 C=zeros(nw,Nf); 0069 S12=zeros(nw,Nf); 0070 S1=zeros(nw,Nf); 0071 S2=zeros(nw,Nf); 0072 phi=zeros(nw,Nf); 0073 Cerr=zeros(2,nw,Nf); 0074 % phierr=zeros(2,nw,Nf); 0075 phistd=zeros(nw,Nf); 0076 else 0077 C=zeros(nw,Nf,Ch); 0078 S12=zeros(nw,Nf,Ch); 0079 S1=zeros(nw,Nf,Ch); 0080 S2=zeros(nw,Nf,Ch); 0081 phi=zeros(nw,Nf,Ch); 0082 Cerr=zeros(2,nw,Nf,Ch); 0083 % phierr=zeros(2,nw,Nf,Ch); 0084 phistd=zeros(nw,Nf,Ch); 0085 end; 0086 0087 for n=1:nw; 0088 indx=winstart(n):winstart(n)+Nwin-1; 0089 datawin1=data1(indx,:);datawin2=data2(indx,:); 0090 if nargout==10; 0091 [c,ph,s12,s1,s2,f,confc,phie,cerr]=coherencyc(datawin1,datawin2,params); 0092 % phierr(1,n,:,:)=squeeze(phie(1,:,:)); 0093 % phierr(2,n,:,:)=squeeze(phie(2,:,:)); 0094 phistd(n,:,:)=phie; 0095 Cerr(1,n,:,:)=squeeze(cerr(1,:,:)); 0096 Cerr(2,n,:,:)=squeeze(cerr(2,:,:)); 0097 elseif nargout==9; 0098 [c,ph,s12,s1,s2,f,confc,phie]=coherencyc(datawin1,datawin2,params); 0099 % phierr(1,n,:,:)=squeeze(phie(1,:,:)); 0100 % phierr(2,n,:,:)=squeeze(phie(2,:,:)); 0101 phistd(n,:,:)=phie; 0102 else 0103 [c,ph,s12,s1,s2,f]=coherencyc(datawin1,datawin2,params); 0104 end; 0105 C(n,:,:)=c; 0106 S12(n,:,:)=s12; 0107 S1(n,:,:)=s1; 0108 S2(n,:,:)=s2; 0109 phi(n,:,:)=ph; 0110 end; 0111 C=squeeze(C); phi=squeeze(phi);S12=squeeze(S12); S1=squeeze(S1); S2=squeeze(S2); 0112 if nargout > 8; confC=confc; end; 0113 if nargout==10;Cerr=squeeze(Cerr);end; 0114 % if nargout>=9; phierr=squeeze(phierr);end 0115 if nargout>=9; phistd=squeeze(phistd);end 0116 winmid=winstart+round(Nwin/2); 0117 t=winmid/Fs;