Home > chronux > spectral_analysis > continuous > mtdspectrumc.m

# mtdspectrumc

## PURPOSE Multi-taper frequency derivative of the spectrum - continuous process

## SYNOPSIS function [dS,f]=mtdspectrumc(data,phi,params)

## DESCRIPTION ``` Multi-taper frequency derivative of the spectrum - continuous process

Usage:

[dS,f]=mtdspectrumc(data,phi,params)
Input:
Note that all times can be in arbitrary units. But the units have to be
consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
times, the units have to be consistent with the units of data as well.
data        (in form samples x channels/trials or a single vector) -- required
phi         (angle for evaluation of derivative) -- required.
e.g. phi=[0,pi/2] gives the time and frequency derivatives
params: structure with fields tapers, pad, Fs, fpass, 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

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
trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
Output:
dS       (spectral derivative in form phi x frequency x channels/trials if trialave=0 or
in form phi x frequency if trialave=1)
f        (frequencies)```

## CROSS-REFERENCE INFORMATION This function calls:
• mtfftc Multi-taper fourier transform - continuous data
This function is called by:
• mtdspecgramc Multi-taper derivative of the time-frequency spectrum - continuous process

## SOURCE CODE ```0001 function [dS,f]=mtdspectrumc(data,phi,params)
0002 % Multi-taper frequency derivative of the spectrum - continuous process
0003 %
0004 % Usage:
0005 %
0006 % [dS,f]=mtdspectrumc(data,phi,params)
0007 % Input:
0008 %   Note that all times can be in arbitrary units. But the units have to be
0009 %   consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
0010 %   be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
0011 %   times, the units have to be consistent with the units of data as well.
0012 %       data        (in form samples x channels/trials or a single vector) -- required
0013 %       phi         (angle for evaluation of derivative) -- required.
0014 %                       e.g. phi=[0,pi/2] gives the time and frequency derivatives
0015 %       params: structure with fields tapers, pad, Fs, fpass, 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 %
0035 %            pad            (padding factor for the FFT) - optional (can take values -1,0,1,2...).
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 %           trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0
0046 % Output:
0047 %       dS       (spectral derivative in form phi x frequency x channels/trials if trialave=0 or
0048 %                in form phi x frequency if trialave=1)
0049 %       f        (frequencies)
0050
0051 if nargin < 2; error('Need data and angle'); end;
0052 if nargin < 3; params=[]; end;
0054 clear err params
0055 data=change_row_to_column(data);
0056 N=size(data,1);
0058 [f,findx]=getfgrid(Fs,nfft,fpass);
0059 tapers=dpsschk(tapers,N,Fs); % check tapers
0060 K=size(tapers,2);
0061 J=mtfftc(data,tapers,nfft,Fs);
0062 J=J(findx,:,:);
0063 A=sqrt(1:K-1);
0064 A=repmat(A,[size(J,1) 1]);
0065 A=repmat(A,[1 1 size(J,3)]);
0066 S=squeeze(mean(J(:,1:K-1,:).*A.*conj(J(:,2:K,:)),2));
0067 if trialave; S=squeeze(mean(S,2));end;
0068 nphi=length(phi);
0069 for p=1:nphi;
0070     dS(p,:,:)=real(exp(i*phi(p))*S);
0071 end;
0072 dS=squeeze(dS);
0073 dS=change_row_to_column(dS);```

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