Index: /trunk/src/transform_field/FFT2_detrend.m
===================================================================
--- /trunk/src/transform_field/FFT2_detrend.m	(revision 510)
+++ /trunk/src/transform_field/FFT2_detrend.m	(revision 510)
@@ -0,0 +1,77 @@
+% 'FFT': calculate and display 2D spectrum of the input scalar
+%  GUI_input=FFT(hget_field)
+%
+% OUTPUT: 
+% GUI_input: option for display in the GUI get_field
+%
+%INPUT:
+% hget_field: handles of the GUI get_field
+%
+
+function DataOut=FFT2_detrend(DataIn)
+%% set GUI config
+DataOut=[];
+if strcmp(DataIn,'*')   
+    DataOut.InputFieldType='scalar';
+    return
+end
+%%%%%%%%%%%%%%%%%%%%%%%%%
+[CellVarIndex,NbDim,CellVarType,errormsg]=find_field_indices(DataIn);
+if ~isempty(errormsg)
+    DataOut.Txt=errormsg;
+    return
+end
+DataOut.ListVarName={};
+DataOut.VarDimName={};
+for ilist=1:numel(CellVarIndex)
+    if NbDim(ilist)==2 && numel(CellVarType{ilist}.coord)==2 % field with structured coordinates
+        %process coordinates
+        CoordName=DataIn.ListVarName(CellVarType{ilist}.coord);
+        x1 = DataIn.(CoordName{2}); y1 = DataIn.(CoordName{1});
+        [x y] = meshgrid(x1,y1);
+        coeff(1,1) = sum(sum(x.^2)); coeff(1,2) = sum(sum(x.*y)); coeff(1,3) = sum(sum(x));
+        coeff(2,1) = sum(sum(x.*y)); coeff(2,2) = sum(sum(y.^2)); coeff(2,3) = sum(sum(y));
+        coeff(3,1) = sum(sum(x)); coeff(3,2) = sum(sum(y)); coeff(3,3) = length(x1)*length(y1);
+        delta_x = x1(2) - x1(1); delta_y = y1(2) - y1(1);
+        Nx = length(x1); Ny = length(y1);
+        Nxa = 1:Nx; Nya = 1:Ny;
+        ssx = find(Nxa<Nx/2); ssy = find(Nya<Ny/2);
+        Nxa(Nx-ssx+1) = -Nxa(ssx)+1; Nya(Ny-ssy+1) = -Nya(ssy)+1;
+        [Nxa Ix] = sort(Nxa); [Nya Iy] = sort(Nya);
+        kx1 = (2*pi/delta_x/Nx)*(Nxa-1); ky1 = (2*pi/delta_y/Ny)*(Nya-1);
+        ss = find(ky1>=0); ky1 = ky1(ss);
+        [kx ky] = meshgrid(kx1,ky1);
+        DataOut.(CoordName{2}) = kx1; DataOut.(CoordName{1}) = ky1;
+        if isfield(DataIn,'CoordUnit')
+            DataOut.CoordUnit=[DataIn.CoordUnit '^{-1}'];
+            DataOut.ListGlobalAttribute={'CoordUnit'};
+        end
+        %process scalar
+        ivar=CellVarType{ilist}.scalar(1);
+        VarName=DataIn.ListVarName{ivar};
+        z=DataIn.(VarName);
+        rhs(1) = sum(sum(x.*z)); rhs(2) = sum(sum(y.*z)); rhs(3) = sum(sum(z));
+        lin_coeff = inv(coeff)*rhs';
+        lin_trend = lin_coeff(1)*x + lin_coeff(2)*y + lin_coeff(3);
+        z2 = z - lin_trend;
+        spec2 = abs(fft2(z2)).^2;
+        spec2 = spec2(Iy,Ix);
+        spec2 = spec2(ss,:);
+        %DataOut.(VarName) = log(spec2);
+        DataOut.(VarName) = spec2;
+        spec_sum=sum(sum(spec2));
+        kx_mean=sum(sum(spec2.*kx))/spec_sum
+        ky_mean=sum(sum(spec2.*ky))/spec_sum
+        theta=atand(ky_mean/kx_mean)
+        lambda=2*pi/(sqrt(kx_mean*kx_mean+ky_mean*ky_mean))
+        %DataOut.ListVarName=[CoordName {VarName} {'kx'} {'ky'}];%list of variables
+        %DataOut.VarDimName=[CoordName {CoordName} {'one'} {'one'}];%list of dimensions for variables
+        
+        DataOut.ListVarName=[CoordName {VarName}];%list of variables
+        DataOut.VarDimName=[CoordName {CoordName}];%list of dimensions for variables
+        break
+    end
+end
+  
+
+