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- <h1>mtspecgramc_fast
- </h1>
- <h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../../up.png"></a></h2>
- <div class="box"><strong>Multi-taper time-frequency spectrum - continuous process</strong></div>
- <h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../../up.png"></a></h2>
- <div class="box"><strong>function [S,t,f,Serr]=mtspecgramc(data,movingwin,params) </strong></div>
- <h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../../up.png"></a></h2>
- <div class="fragment"><pre class="comment"> 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
- has to be in Hz. see chronux.m for more information.
- 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. Defaults to 0.
- e.g. For N = 500, if PAD = 0, we pad the FFT
- to 512 points; if PAD = 2, we pad the FFT
- to 2048 points, etc.
- 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</pre></div>
- <!-- crossreference -->
- <h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../../up.png"></a></h2>
- This function calls:
- <ul style="list-style-image:url(../../matlabicon.gif)">
- <li><a href="../../chronux_2_10/spectral_analysis/helper/dpsschk.html" class="code" title="function [tapers,eigs]=dpsschk(tapers,N,Fs)">dpsschk</a> Helper function to calculate tapers and, if precalculated tapers are supplied,</li><li><a href="../../chronux_2_10/spectral_analysis/helper/getfgrid.html" class="code" title="function [f,findx]=getfgrid(Fs,nfft,fpass)">getfgrid</a> Helper function that gets the frequency grid associated with a given fft based computation</li><li><a href="../../chronux_2_10/spectral_analysis/helper/getparams.html" class="code" title="function [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params)">getparams</a> Helper function to convert structure params to variables used by the</li></ul>
- This function is called by:
- <ul style="list-style-image:url(../../matlabicon.gif)">
- </ul>
- <!-- crossreference -->
- <h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../../up.png"></a></h2>
- <div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function [S,t,f,Serr]=mtspecgramc(data,movingwin,params)</a>
- 0002 <span class="comment">% Multi-taper time-frequency spectrum - continuous process</span>
- 0003 <span class="comment">%</span>
- 0004 <span class="comment">% Usage:</span>
- 0005 <span class="comment">% [S,t,f,Serr]=mtspecgramc(data,movingwin,params)</span>
- 0006 <span class="comment">% Input:</span>
- 0007 <span class="comment">% Note units have to be consistent. Thus, if movingwin is in seconds, Fs</span>
- 0008 <span class="comment">% has to be in Hz. see chronux.m for more information.</span>
- 0009 <span class="comment">% data (in form samples x channels/trials) -- required</span>
- 0010 <span class="comment">% movingwin (in the form [window winstep] i.e length of moving</span>
- 0011 <span class="comment">% window and step size)</span>
- 0012 <span class="comment">% Note that units here have</span>
- 0013 <span class="comment">% to be consistent with</span>
- 0014 <span class="comment">% units of Fs - required</span>
- 0015 <span class="comment">% params: structure with fields tapers, pad, Fs, fpass, err, trialave</span>
- 0016 <span class="comment">% - optional</span>
- 0017 <span class="comment">% tapers : precalculated tapers from dpss or in the one of the following</span>
- 0018 <span class="comment">% forms:</span>
- 0019 <span class="comment">% (1) A numeric vector [TW K] where TW is the</span>
- 0020 <span class="comment">% time-bandwidth product and K is the number of</span>
- 0021 <span class="comment">% tapers to be used (less than or equal to</span>
- 0022 <span class="comment">% 2TW-1).</span>
- 0023 <span class="comment">% (2) A numeric vector [W T p] where W is the</span>
- 0024 <span class="comment">% bandwidth, T is the duration of the data and p</span>
- 0025 <span class="comment">% is an integer such that 2TW-p tapers are used. In</span>
- 0026 <span class="comment">% this form there is no default i.e. to specify</span>
- 0027 <span class="comment">% the bandwidth, you have to specify T and p as</span>
- 0028 <span class="comment">% well. Note that the units of W and T have to be</span>
- 0029 <span class="comment">% consistent: if W is in Hz, T must be in seconds</span>
- 0030 <span class="comment">% and vice versa. Note that these units must also</span>
- 0031 <span class="comment">% be consistent with the units of params.Fs: W can</span>
- 0032 <span class="comment">% be in Hz if and only if params.Fs is in Hz.</span>
- 0033 <span class="comment">% The default is to use form 1 with TW=3 and K=5</span>
- 0034 <span class="comment">% Note that T has to be equal to movingwin(1).</span>
- 0035 <span class="comment">%</span>
- 0036 <span class="comment">% pad (padding factor for the FFT) - optional. Defaults to 0.</span>
- 0037 <span class="comment">% e.g. For N = 500, if PAD = 0, we pad the FFT</span>
- 0038 <span class="comment">% to 512 points; if PAD = 2, we pad the FFT</span>
- 0039 <span class="comment">% to 2048 points, etc.</span>
- 0040 <span class="comment">% Fs (sampling frequency) - optional. Default 1.</span>
- 0041 <span class="comment">% fpass (frequency band to be used in the calculation in the form</span>
- 0042 <span class="comment">% [fmin fmax])- optional.</span>
- 0043 <span class="comment">% Default all frequencies between 0 and Fs/2</span>
- 0044 <span class="comment">% err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars</span>
- 0045 <span class="comment">% [0 p] or 0 - no error bars) - optional. Default 0.</span>
- 0046 <span class="comment">% trialave (average over trials/channels when 1, don't average when 0) - optional. Default 0</span>
- 0047 <span class="comment">% Output:</span>
- 0048 <span class="comment">% S (spectrum in form time x frequency x channels/trials if trialave=0; in the form time x frequency if trialave=1)</span>
- 0049 <span class="comment">% t (times)</span>
- 0050 <span class="comment">% f (frequencies)</span>
- 0051 <span class="comment">% Serr (error bars) only for err(1)>=1</span>
- 0052
- 0053 <span class="keyword">if</span> nargin < 2; error(<span class="string">'Need data and window parameters'</span>); <span class="keyword">end</span>;
- 0054 <span class="keyword">if</span> nargin < 3; params=[]; <span class="keyword">end</span>;
- 0055
- 0056 <span class="keyword">if</span> length(params.tapers)==3 & movingwin(1)~=params.tapers(2);
- 0057 error(<span class="string">'Duration of data in params.tapers is inconsistent with movingwin(1), modify params.tapers(2) to proceed'</span>)
- 0058 <span class="keyword">end</span>
- 0059
- 0060 [tapers,pad,Fs,fpass,err,trialave,params]=<a href="../../chronux_2_10/spectral_analysis/helper/getparams.html" class="code" title="function [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params)">getparams</a>(params);
- 0061 <span class="keyword">if</span> nargout > 3 && err(1)==0;
- 0062 <span class="comment">% Cannot compute error bars with err(1)=0. change params and run again.</span>
- 0063 error(<span class="string">'When Serr is desired, err(1) has to be non-zero.'</span>);
- 0064 <span class="keyword">end</span>;
- 0065
- 0066 N=size(data,1);
- 0067 Nwin=round(Fs*movingwin(1)); <span class="comment">% number of samples in window</span>
- 0068 Nstep=round(movingwin(2)*Fs); <span class="comment">% number of samples to step through</span>
- 0069 nfft=2^(nextpow2(Nwin)+pad);
- 0070
- 0071 [f,findx]=<a href="../../chronux_2_10/spectral_analysis/helper/getfgrid.html" class="code" title="function [f,findx]=getfgrid(Fs,nfft,fpass)">getfgrid</a>(Fs,nfft,fpass);
- 0072 tapers=<a href="../../chronux_2_10/spectral_analysis/helper/dpsschk.html" class="code" title="function [tapers,eigs]=dpsschk(tapers,N,Fs)">dpsschk</a>(tapers,Nwin,Fs); <span class="comment">% check tapers</span>
- 0073 [NC C]=size(data); <span class="comment">% size of data</span>
- 0074 [NK K]=size(tapers); <span class="comment">% size of tapers</span>
- 0075
- 0076 tapers=tapers(:,:,ones(1,C)); <span class="comment">% add channel indices to tapers</span>
- 0077
- 0078 <span class="keyword">if</span> NK~=Nwin ; error(<span class="string">'length of tapers is incompatible with length of data'</span>); <span class="keyword">end</span>;
- 0079
- 0080 winstart=1:Nstep:N-Nwin+1;
- 0081 nw=length(winstart);
- 0082
- 0083 S = zeros(nw,length(f),C);
- 0084
- 0085 <span class="keyword">for</span> n=1:nw;
- 0086 J=fft((permute(data(winstart(n):winstart(n)+Nwin-1,:,ones(1,K)),[1 3 2]) .* tapers) ,nfft)/Fs; <span class="comment">% fft of projected data</span>
- 0087 J=J(findx,:,:);
- 0088 S(n,:,:)=squeeze(mean(conj(J).*J,2));
- 0089 <span class="keyword">end</span>
- 0090
- 0091 <span class="keyword">if</span> nargout==4;Serr=squeeze(Serr);<span class="keyword">end</span>;
- 0092 winmid=winstart+round(Nwin/2);
- 0093 t=winmid/Fs;</pre></div>
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