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 one of the following
forms:
(1) A numeric vector [TW K] where TW is the
time-bandwidth product and K is the number of
tapers to be used (less than or equal to
2TW-1).
(2) A numeric vector [W T p] where W is the
bandwidth, T is the duration of the data and p
is an integer such that 2TW-p tapers are used. In
this form there is no default i.e. to specify
the bandwidth, you have to specify T and p as
well. Note that the units of W and T have to be
consistent: if W is in Hz, T must be in seconds
and vice versa. Note that these units must also
be consistent with the units of params.Fs: W can
be in Hz if and only if params.Fs is in Hz.
The default is to use form 1 with TW=3 and K=5
Note that T has to be equal to movingwin(1).
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 one of the following 0017 % forms: 0018 % (1) A numeric vector [TW K] where TW is the 0019 % time-bandwidth product and K is the number of 0020 % tapers to be used (less than or equal to 0021 % 2TW-1). 0022 % (2) A numeric vector [W T p] where W is the 0023 % bandwidth, T is the duration of the data and p 0024 % is an integer such that 2TW-p tapers are used. In 0025 % this form there is no default i.e. to specify 0026 % the bandwidth, you have to specify T and p as 0027 % well. Note that the units of W and T have to be 0028 % consistent: if W is in Hz, T must be in seconds 0029 % and vice versa. Note that these units must also 0030 % be consistent with the units of params.Fs: W can 0031 % be in Hz if and only if params.Fs is in Hz. 0032 % The default is to use form 1 with TW=3 and K=5 0033 % Note that T has to be equal to movingwin(1). 0034 % 0035 % pad (padding factor for the FFT) - optional (can take values -1,0,1,2...). 0036 % -1 corresponds to no padding, 0 corresponds to padding 0037 % to the next highest power of 2 etc. 0038 % e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT 0039 % to 512 points, if pad=1, we pad to 1024 points etc. 0040 % Defaults to 0. 0041 % Fs (sampling frequency) - optional. Default 1. 0042 % fpass (frequency band to be used in the calculation in the form 0043 % [fmin fmax])- optional. 0044 % Default all frequencies between 0 and Fs/2 0045 % err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars 0046 % [0 p] or 0 - no error bars) - optional. Default 0. 0047 % trialave (average over trials when 1, don't average when 0) - optional. Default 0 0048 % Output: 0049 % C (magnitude of coherency time x frequencies x trials for trialave=0; 0050 % time x frequency for trialave=1) 0051 % phi (phase of coherency time x frequencies x trials for no trial averaging; 0052 % time x frequency for trialave=1) 0053 % S12 (cross spectrum - time x frequencies x trials for no trial averaging; 0054 % time x frequency for trialave=1) 0055 % S1 (spectrum 1 - time x frequencies x trials for no trial averaging; 0056 % time x frequency for trialave=1) 0057 % S2 (spectrum 2 - time x frequencies x trials for no trial averaging; 0058 % time x frequency for trialave=1) 0059 % t (time) 0060 % f (frequencies) 0061 % confC (confidence level for C at 1-p %) - only for err(1)>=1 0062 % phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi 0063 % Note that phi + 2 phistd and phi - 2 phistd will give 95% confidence 0064 % bands for phi - only for err(1)>=1 0065 % Cerr (Jackknife error bars for C - use only for Jackknife - err(1)=2) 0066 0067 if nargin < 3; error('Need data1 and data2 and window parameters'); end; 0068 if nargin < 4; params=[];end; 0069 0070 if length(params.tapers)==3 & movingwin(1)~=params.tapers(2); 0071 error('Duration of data in params.tapers is inconsistent with movingwin(1), modify params.tapers(2) to proceed') 0072 end 0073 0074 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0075 0076 if nargout > 9 && err(1)~=2; 0077 error('Cerr computed only for Jackknife. Correct inputs and run again'); 0078 end; 0079 if nargout > 7 && err(1)==0; 0080 % Errors computed only if err(1) is nonzero. Need to change params and run again. 0081 error('When errors are desired, err(1) has to be non-zero.'); 0082 end; 0083 [N,Ch]=check_consistency(data1,data2); 0084 0085 Nwin=round(Fs*movingwin(1)); % number of samples in window 0086 Nstep=round(movingwin(2)*Fs); % number of samples to step through 0087 nfft=max(2^(nextpow2(Nwin)+pad),Nwin); 0088 f=getfgrid(Fs,nfft,fpass); 0089 Nf=length(f); 0090 params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers 0091 0092 winstart=1:Nstep:N-Nwin+1; 0093 nw=length(winstart); 0094 if trialave; 0095 C=zeros(nw,Nf); 0096 S12=zeros(nw,Nf); 0097 S1=zeros(nw,Nf); 0098 S2=zeros(nw,Nf); 0099 phi=zeros(nw,Nf); 0100 Cerr=zeros(2,nw,Nf); 0101 % phierr=zeros(2,nw,Nf); 0102 phistd=zeros(nw,Nf); 0103 else 0104 C=zeros(nw,Nf,Ch); 0105 S12=zeros(nw,Nf,Ch); 0106 S1=zeros(nw,Nf,Ch); 0107 S2=zeros(nw,Nf,Ch); 0108 phi=zeros(nw,Nf,Ch); 0109 Cerr=zeros(2,nw,Nf,Ch); 0110 % phierr=zeros(2,nw,Nf,Ch); 0111 phistd=zeros(nw,Nf,Ch); 0112 end; 0113 0114 for n=1:nw; 0115 indx=winstart(n):winstart(n)+Nwin-1; 0116 datawin1=data1(indx,:);datawin2=data2(indx,:); 0117 if nargout==10; 0118 [c,ph,s12,s1,s2,f,confc,phie,cerr]=coherencyc(datawin1,datawin2,params); 0119 % phierr(1,n,:,:)=squeeze(phie(1,:,:)); 0120 % phierr(2,n,:,:)=squeeze(phie(2,:,:)); 0121 phistd(n,:,:)=phie; 0122 Cerr(1,n,:,:)=squeeze(cerr(1,:,:)); 0123 Cerr(2,n,:,:)=squeeze(cerr(2,:,:)); 0124 elseif nargout==9; 0125 [c,ph,s12,s1,s2,f,confc,phie]=coherencyc(datawin1,datawin2,params); 0126 % phierr(1,n,:,:)=squeeze(phie(1,:,:)); 0127 % phierr(2,n,:,:)=squeeze(phie(2,:,:)); 0128 phistd(n,:,:)=phie; 0129 else 0130 [c,ph,s12,s1,s2,f]=coherencyc(datawin1,datawin2,params); 0131 end; 0132 C(n,:,:)=c; 0133 S12(n,:,:)=s12; 0134 S1(n,:,:)=s1; 0135 S2(n,:,:)=s2; 0136 phi(n,:,:)=ph; 0137 end; 0138 C=squeeze(C); phi=squeeze(phi);S12=squeeze(S12); S1=squeeze(S1); S2=squeeze(S2); 0139 if nargout > 8; confC=confc; end; 0140 if nargout==10;Cerr=squeeze(Cerr);end; 0141 % if nargout>=9; phierr=squeeze(phierr);end 0142 if nargout>=9; phistd=squeeze(phistd);end 0143 winmid=winstart+round(Nwin/2); 0144 t=winmid/Fs;