--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@ao/ifft_core.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,79 @@
+% IFFT_CORE Simple core method which computes the ifft.
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: Simple core method which computes the ifft.
+%
+% CALL:        ao = ifft_core(ao, type)
+%
+% INPUTS:      ao:   Single input analysis object
+%              type: The ifft type
+%                    'symmetric'
+%                    'nonsymmetric'
+%
+% VERSION:     $Id: ifft_core.m,v 1.6 2011/02/14 19:33:35 ingo Exp $
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+function bs = ifft_core(bs, type)
+  
+  switch class(bs.data)
+    case {'fsdata'}
+      fs     = bs.data.fs;
+      % check fft type
+      if any((bs.data.x)<0) % two sided fft
+        utils.helper.msg(utils.const.msg.PROC1, 'two sided fft');
+        y = ifftshift(bs.data.y);
+      else
+        % get minimum frequency step
+        df = bs.data.x(end)-bs.data.x(end-1);
+        if abs(((fs-df)-bs.data.x(end)))<eps % plain fft
+          utils.helper.msg(utils.const.msg.PROC1, 'plain fft');
+          y = bs.data.y;
+        elseif abs((bs.data.x(end)-fs/2))<eps % onesided fft even nfft
+          utils.helper.msg(utils.const.msg.PROC1, 'one sided fft even nfft');
+          y1 = bs.data.y(1:end);
+          y2 = conj(bs.data.y(end-1:-1:2));
+          if size(y1,1)==1 % raw
+            y = [y1 y2];
+          else
+            y = [y1;y2];
+          end
+        else % onesided fft odd nfft
+          utils.helper.msg(utils.const.msg.PROC1, 'one sided fft odd nfft');
+          y1 = bs.data.y(1:end);
+          y2 = conj(bs.data.y(end:-1:2));
+          if size(y1,1)==1 % raw
+            y = [y1 y2];
+          else
+            y = [y1;y2];
+          end
+        end
+      end
+
+      y    = ifft(y, type);
+      % Keep the data shape if the input AO
+      if size(bs.data.y, 1) == 1
+        y = y.';
+      end
+
+      % make a new tsdata object
+      fsd = tsdata(y, fs);
+      fsd.setXunits('s');
+      fsd.setYunits(bs.yunits);
+      
+      % Set data
+      bs.data = fsd;
+      % clear errors
+      bs.clearErrors;
+      
+    case {'tsdata', 'cdata', 'xydata'}
+      error('### I don''t work for time-series, constant or x/y data.');
+    otherwise
+      error('### unknown data type.')
+  end
+  
+  
+end
+
+
+
+