Home > chronux > spectral_analysis > continuous > mtspecgramc.m

# mtspecgramc

## PURPOSE Multi-taper time-frequency spectrum - continuous process

## SYNOPSIS function [S,t,f,Serr]=mtspecgramc(data,movingwin,params)

## DESCRIPTION ``` Multi-taper time-frequency spectrum - continuous process

Usage:
[S,t,f,Serr]=mtspecgramc(data,movingwin,params)
Input:
Note units have to be consistent. Thus, if movingwin is in seconds, Fs
data        (in form samples x channels/trials) -- required
movingwin         (in the form [window winstep] i.e length of moving
window and step size)
Note that units here have
to be consistent with
units of Fs - 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...).
to the next highest power of 2 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/channels when 1, don't average when 0) - optional. Default 0
Output:
S       (spectrum in form time x frequency x channels/trials if trialave=0;
in the form time x frequency if trialave=1)
t       (times)
f       (frequencies)
Serr    (error bars) only for err(1)>=1```

## CROSS-REFERENCE INFORMATION This function calls:
This function is called by:
• mtspecgramtrigc Multi-taper event triggered time-frequency spectrum - continuous process

## SOURCE CODE ```0001 function [S,t,f,Serr]=mtspecgramc(data,movingwin,params)
0002 % Multi-taper time-frequency spectrum - continuous process
0003 %
0004 % Usage:
0005 % [S,t,f,Serr]=mtspecgramc(data,movingwin,params)
0006 % Input:
0007 % Note units have to be consistent. Thus, if movingwin is in seconds, Fs
0008 % has to be in Hz. see chronux.m for more information.
0009 %       data        (in form samples x channels/trials) -- required
0010 %       movingwin         (in the form [window winstep] i.e length of moving
0011 %                                                 window and step size)
0012 %                                                 Note that units here have
0013 %                                                 to be consistent with
0014 %                                                 units of Fs - required
0015 %       params: structure with fields tapers, pad, Fs, fpass, err, trialave
0016 %       - optional
0017 %           tapers : precalculated tapers from dpss or in the one of the following
0018 %                    forms:
0019 %                    (1) A numeric vector [TW K] where TW is the
0020 %                        time-bandwidth product and K is the number of
0021 %                        tapers to be used (less than or equal to
0022 %                        2TW-1).
0023 %                    (2) A numeric vector [W T p] where W is the
0024 %                        bandwidth, T is the duration of the data and p
0025 %                        is an integer such that 2TW-p tapers are used. In
0026 %                        this form there is no default i.e. to specify
0027 %                        the bandwidth, you have to specify T and p as
0028 %                        well. Note that the units of W and T have to be
0029 %                        consistent: if W is in Hz, T must be in seconds
0030 %                        and vice versa. Note that these units must also
0031 %                        be consistent with the units of params.Fs: W can
0032 %                        be in Hz if and only if params.Fs is in Hz.
0033 %                        The default is to use form 1 with TW=3 and K=5
0034 %                     Note that T has to be equal to movingwin(1).
0035 %
0036 %            pad            (padding factor for the FFT) - optional (can take values -1,0,1,2...).
0038 %                    to the next highest power of 2 etc.
0039 %                       e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
0040 %                       to 512 points, if pad=1, we pad to 1024 points etc.
0041 %                       Defaults to 0.
0042 %           Fs   (sampling frequency) - optional. Default 1.
0043 %           fpass    (frequency band to be used in the calculation in the form
0044 %                                   [fmin fmax])- optional.
0045 %                                   Default all frequencies between 0 and Fs/2
0046 %           err  (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
0047 %                                   [0 p] or 0 - no error bars) - optional. Default 0.
0048 %           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
0049 % Output:
0050 %       S       (spectrum in form time x frequency x channels/trials if trialave=0;
0051 %               in the form time x frequency if trialave=1)
0052 %       t       (times)
0053 %       f       (frequencies)
0054 %       Serr    (error bars) only for err(1)>=1
0055
0056 if nargin < 2; error('Need data and window parameters'); end;
0057 if nargin < 3; params=[]; end;
0058
0060 if length(params.tapers)==3 & movingwin(1)~=params.tapers(2);
0061     error('Duration of data in params.tapers is inconsistent with movingwin(1), modify params.tapers(2) to proceed')
0062 end
0063
0064 if nargout > 3 && err(1)==0;
0065 %   Cannot compute error bars with err(1)=0. change params and run again.
0066     error('When Serr is desired, err(1) has to be non-zero.');
0067 end;
0068 data=change_row_to_column(data);
0069 [N,Ch]=size(data);
0070 Nwin=round(Fs*movingwin(1)); % number of samples in window
0071 Nstep=round(movingwin(2)*Fs); % number of samples to step through
0073 f=getfgrid(Fs,nfft,fpass); Nf=length(f);
0074 params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers
0075
0076 winstart=1:Nstep:N-Nwin+1;
0077 nw=length(winstart);
0078
0079 if trialave
0080     S = zeros(nw,Nf);
0081     if nargout==4; Serr=zeros(2,nw,Nf); end;
0082 else
0083     S = zeros(nw,Nf,Ch);
0084     if nargout==4; Serr=zeros(2,nw,Nf,Ch); end;
0085 end
0086
0087 for n=1:nw;
0088    indx=winstart(n):winstart(n)+Nwin-1;
0089    datawin=data(indx,:);
0090    if nargout==4
0091      [s,f,serr]=mtspectrumc(datawin,params);
0092      Serr(1,n,:,:)=squeeze(serr(1,:,:));
0093      Serr(2,n,:,:)=squeeze(serr(2,:,:));
0094    else
0095      [s,f]=mtspectrumc(datawin,params);
0096    end
0097    S(n,:,:)=s;
0098 end;
0099 S=squeeze(S);
0100 if nargout==4;Serr=squeeze(Serr);end;
0101 winmid=winstart+round(Nwin/2);
0102 t=winmid/Fs;```

Generated on Fri 28-Sep-2012 12:34:30 by m2html © 2005