Home > chronux > spectral_analysis > continuous > coherencysegc.m

coherencysegc

PURPOSE ^

Multi-taper coherency, cross-spectrum and individual spectra with segmenting - continuous process

SYNOPSIS ^

function [C,phi,S12,S1,S2,f,confC,phistd,Cerr]=coherencysegc(data1,data2,win,params)

DESCRIPTION ^

 Multi-taper coherency, cross-spectrum and individual spectra with segmenting - continuous process
   computed by segmenting two univariate time series into chunks

 Usage:
 [C,phi,S12,S1,S2,f,confC,phistd,Cerr]=coherencysegc(data1,data2,win,params)
 Input: 
 Note units have to be consistent. See chronux.m for more information.
       data1 (column vector) -- required
       data2 (column vector) -- required
       win   (length of segments) - required
       params: structure with fields tapers, pad, Fs, fpass, err
       - 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

            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.
 Output:
       C (magnitude of coherency - frequencies x segments if segave=0; dimension frequencies if segave=1)
       phi (phase of coherency - frequencies x segments if segave=0; dimension frequencies if segave=1)
       S12 (cross spectrum -  frequencies x segments if segave=0; dimension frequencies if segave=1)
       S1 (spectrum 1 - frequencies x segments if segave=0; dimension frequencies if segave=1)
       S2 (spectrum 2 - frequencies x segments if segave=0; dimension frequencies if segave=1)
       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)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [C,phi,S12,S1,S2,f,confC,phistd,Cerr]=coherencysegc(data1,data2,win,params)
0002 % Multi-taper coherency, cross-spectrum and individual spectra with segmenting - continuous process
0003 %   computed by segmenting two univariate time series into chunks
0004 %
0005 % Usage:
0006 % [C,phi,S12,S1,S2,f,confC,phistd,Cerr]=coherencysegc(data1,data2,win,params)
0007 % Input:
0008 % Note units have to be consistent. See chronux.m for more information.
0009 %       data1 (column vector) -- required
0010 %       data2 (column vector) -- required
0011 %       win   (length of segments) - required
0012 %       params: structure with fields tapers, pad, Fs, fpass, err
0013 %       - optional
0014 %           tapers : precalculated tapers from dpss or in the one of the following
0015 %                    forms:
0016 %                    (1) A numeric vector [TW K] where TW is the
0017 %                        time-bandwidth product and K is the number of
0018 %                        tapers to be used (less than or equal to
0019 %                        2TW-1).
0020 %                    (2) A numeric vector [W T p] where W is the
0021 %                        bandwidth, T is the duration of the data and p
0022 %                        is an integer such that 2TW-p tapers are used. In
0023 %                        this form there is no default i.e. to specify
0024 %                        the bandwidth, you have to specify T and p as
0025 %                        well. Note that the units of W and T have to be
0026 %                        consistent: if W is in Hz, T must be in seconds
0027 %                        and vice versa. Note that these units must also
0028 %                        be consistent with the units of params.Fs: W can
0029 %                        be in Hz if and only if params.Fs is in Hz.
0030 %                        The default is to use form 1 with TW=3 and K=5
0031 %
0032 %            pad            (padding factor for the FFT) - optional (can take values -1,0,1,2...).
0033 %                    -1 corresponds to no padding, 0 corresponds to padding
0034 %                    to the next highest power of 2 etc.
0035 %                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
0036 %                       to 512 points, if pad=1, we pad to 1024 points etc.
0037 %                       Defaults to 0.
0038 %           Fs   (sampling frequency) - optional. Default 1.
0039 %           fpass    (frequency band to be used in the calculation in the form
0040 %                                   [fmin fmax])- optional.
0041 %                                   Default all frequencies between 0 and Fs/2
0042 %           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
0043 %                                   [0 p] or 0 - no error bars) - optional. Default 0.
0044 % Output:
0045 %       C (magnitude of coherency - frequencies x segments if segave=0; dimension frequencies if segave=1)
0046 %       phi (phase of coherency - frequencies x segments if segave=0; dimension frequencies if segave=1)
0047 %       S12 (cross spectrum -  frequencies x segments if segave=0; dimension frequencies if segave=1)
0048 %       S1 (spectrum 1 - frequencies x segments if segave=0; dimension frequencies if segave=1)
0049 %       S2 (spectrum 2 - frequencies x segments if segave=0; dimension frequencies if segave=1)
0050 %       f (frequencies)
0051 %       confC (confidence level for C at 1-p %) - only for err(1)>=1
0052 %       phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi
0053 %                Note that phi + 2 phistd and phi - 2 phistd will give 95% confidence
0054 %                bands for phi - only for err(1)>=1
0055 %       Cerr  (Jackknife error bars for C - use only for Jackknife - err(1)=2)
0056 
0057 if nargin < 3; error('Need data1 and data2 and size of segment'); end;
0058 if nargin < 4; params=[]; end;
0059 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params);
0060 clear tapers pad fpass trialave
0061 if nargout > 8 && err(1)~=2; 
0062     error('Cerr computed only for Jackknife. Correct inputs and run again');
0063 end;
0064 if nargout > 6 && err(1)==0;
0065 %   Errors computed only if err(1) is nonzero. Need to change params and run again.
0066     error('When errors are desired, err(1) has to be non-zero.');
0067 end;
0068 if size(data1,2)~=1 || size(data2,2)~=1; error('works for only univariate time series'); end;
0069 
0070 N=check_consistency(data1,data2);
0071 
0072 dt=1/Fs; % sampling interval
0073 T=N*dt; % length of data in seconds
0074 E=0:win:T-win; % fictitious event triggers
0075 win=[0 win]; % use window length to define left and right limits of windows around triggers
0076 data1=createdatamatc(data1,E,Fs,win); % segmented data 1
0077 data2=createdatamatc(data2,E,Fs,win); % segmented data 2
0078 params.trialave=1;
0079 params.trialave=1;
0080 if err==0;
0081    [C,phi,S12,S1,S2,f]=coherencyc(data1,data2,params); % compute coherency for segmented data
0082 elseif err(1)==1;
0083    [C,phi,S12,S1,S2,f,confC,phistd]=coherencyc(data1,data2,params); % compute coherency for segmented data
0084 elseif err(1)==2;
0085    [C,phi,S12,S1,S2,f,confC,phistd,Cerr]=coherencyc(data1,data2,params); % compute coherency for segmented data
0086 end;

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