root/adcp/trunk/adcp/diwasp_1_1GD/dirspec.m

function [SM,EP]=dirspec(ID,SM,EP,varargin);

%DIWASP V1.1 function with GD edit
%dirspec: main spectral estimation routine
%
%Note that there have been some chages made to this function since V1.1
%
%-The outdated matlab function csd was replaced with the new version cpsd on
%line 90
%
%-The ability to use along beam radial velocities has been added, and so the transfer 
%parameters have been edited (line 109) so that the x,y position of the data input
%is also included
%
%-In addition, the first data input cell is radial velocity data, the initial 1-d
%frequency spectrum will be generated using the spectral average of all of
%the data input.  Note that if the first data input cell is something other
%than 'radial' (pressure or sea surface height may be preferable), 
%the initial 1-d frequency spectrum will be generated using ONLY that first
%data input.  (see line 123) 
%
%
%[SMout,EPout]=dirspec(ID,SM,EP,{options})
%
%Outputs:
%SMout      A spectral matrix structure containing the results
%Epout          The estimation parameters structure with the values actually used for the computation including any default settings.
%
%Inputs:
%ID                     An instrument data structure containing the measured data
%SM             A spectral matrix structure; data in field SM.S is ignored.
%EP                 The estimation parameters structure. For default values enter EP as []
%[options]  options entered as cell array with parameter/value pairs: e.g.{'MESSAGE',1,'PLOTTYPE',2};
%                Available options with default values:
%                    'MESSAGE',1,    Level of screen display: 0,1,2 (increasing output)
%                    'PLOTTYPE',1,   Plot type: 0 none, 1 3d surface, 2 polar type plot, 3 3d surface(compass angles), 4 polar plot(compass angles)
%                    'FILEOUT',''        Filename for output file: empty string means no file output
%                
%Input structures ID and SM are required. Either [EP] or [options] can be included but must be in order if both are included.
%Type:%"help data_structures" for information on the DIWASP data structures

%All of the implemented calculation algorithms are as described by:
%Hashimoto,N. 1997 "Analysis of the directional wave spectrum from field data" 
%In: Advances in Coastal Engineering Vol.3. Ed:Liu,P.L-F. Pub:World Scientific,Singapore
%
%Copyright (C) 2002 Coastal Oceanography Group, CWR, UWA, Perth

Options=struct('MESSAGE',1,'PLOTTYPE',1,'FILEOUT','');

if nargin<3
   error('All inputs other than OPTIONS required');
elseif nargin>=4
   nopts=length(varargin{1});
end

ID=check_data(ID,1);if isempty(ID) return;end;
SM=check_data(SM,2);if isempty(SM) return;end;
EP=check_data(EP,3);if isempty(EP) return;end;

if ~isempty(nopts)
if(rem(nopts,2)~=0)
        warning('Options must be in Name/Value pairs - setting to defaults');
        else
        for i=1:(nopts/2)
        arg=varargin{1}{(2*i)};
        field=varargin{1}{(2*i-1)};
        Options=setfield(Options,field,arg);end;end   
end

ptype=Options.PLOTTYPE;displ=Options.MESSAGE;

disp(' ');disp('calculating.....');disp(' ');disp('cross power spectra');

data=detrend(ID.data);
szd=size(ID.data,2);
dt=1/(ID.fs);

%get resolution of FFT - if not specified, calculate a sensible value depending on sampling frequency
if isempty(EP.nfft)
    nfft=2^(8+round(log2(ID.fs)));
    EP.nfft=nfft;
else
    nfft=EP.nfft;
end

% NOTE: changed from csd to cpsd 6/15/07
%calculate the cross-power spectra
for m=1:szd
for n=1:szd
   [xpstmp,Ftmp]=cpsd(data(:,m),data(:,n),[],[],nfft,ID.fs);
   xps(m,n,:)=xpstmp(2:(nfft/2)+1);
 end
end

F=Ftmp(2:(nfft/2)+1);nf=nfft/2;

%calculate wavenumbers
disp('wavenumbers')
wns=wavenumber(2*pi*F,ID.depth*ones(size(F)));
pidirs=[-pi:(2*pi/EP.dres):pi-(2*pi/EP.dres)]; % this is dirs

%  NOTE:  edited the transfer parameters to include x and y position
%  x is (layout(1,m)),y is (layout(2,m))   (6/15/07)

%calculate transfer parameters
disp('transfer parameters');
disp(' ');
for m=1:szd
        trm(m,:,:)=feval(ID.datatypes{m},2*pi*F,pidirs,wns,ID.layout(3,m),ID.depth,ID.layout(1,m),ID.layout(2,m)); % 2piF is ffreqs
 for n=1:szd
    kx(m,n,:,:)=wns*((ID.layout(1,n)-ID.layout(1,m))*cos(pidirs)+(ID.layout(2,n)-ID.layout(2,m))*sin(pidirs));
end
end

for m=1:szd
   tfn(:,:)=trm(m,:,:);
   Sxps(1:nf)=2*dt*xps(m,m,:);
   Ss(m,:)=Sxps./(max(tfn').*conj(max(tfn')));
end

%have Ss = the spectral average if the radial velocities are used without a
%pressure or vertical range datatype first
compare=strcmp('radial',ID.datatypes(1));

if compare == 1
    Ss=mean(Ss);
end
    
ffs=sum(F<=max(SM.freqs));

    % call appropriate estimation function
disp(['directional spectra using' blanks(1) EP.method ' method']);disp(' ')
Specout=feval(EP.method,xps(:,:,1:ffs),trm(:,1:ffs,:),kx(:,:,1:ffs,:),Ss(:,1:ffs),pidirs,EP.iter,displ);

Specout(find(isnan(Specout)))=0.0;
Hs=Hsig(Specout,F(2)-F(1),pidirs(2)-pidirs(1));

% map spectrum onto user defined spectrum matrix - need extra line of frequencies to avoid NaNs
[df,ddir]=meshgrid(SM.freqs,SM.dirs);
pidirs(EP.dres+1)=pi;
Specout=Specout';
Specout(EP.dres+1,:)=Specout(1,:);
[Ff,Dd]=meshgrid(F(1:ffs),(180/pi)*pidirs);
S=interp2(Ff,Dd,Specout,df,ddir,'nearest');
S=S*pi/180;
S(find(isnan(S)))=0.0;

%check Hsig of mapped spectrum and check sufficiently close to original
Hs2=Hsig(S,SM.freqs(2)-SM.freqs(1),SM.dirs(2)-SM.dirs(1));
if (Hs2-Hs)/Hs >0.01
    warning('User defined grid may be too coarse; try increasing resolution of ''SM.freqs'' or ''SM.dirs''');
end

%smooth spectrum
if(strcmp(EP.smooth,'ON'))
    disp(' ');disp('smoothing spectrum...');disp(' ');
    S=smoothspec(S,[1 0.5 0.25;1 0.5 0.25]);
end
SM.S=S';

infospec(SM);

%write out spectrum matrix in DIWASP format
filename=Options.FILEOUT;
if(size(filename,2)>0)
   disp('writing out spectrum matrix to file');
   writespec(SM,filename);
end

%plot spectrum
if(ptype>0)
    disp('finished...plotting spectrum');
    plotspec(SM,ptype);
    T=['Directional spectrum estimated using ' blanks(1) EP.method ' method'];title(T);
end