Fixed a critical wfs_preequalization() bug.

Before the filter does not work properly for ir_wfs(). Note that this bug was
newly introduced for the 1.0.0 version and worked fine in older versions

SFS_time_domain/sound_field_imp_wfs.m

@@ -87,6 +87,7 @@
 else
  greens_function = 'ps';
 end
+usehpre = conf.wfs.usehpre;
 
 
 %% ===== Computation =====================================================
@@ -96,6 +97,12 @@
 x0 = secondary_source_tapering(x0,conf);
 % Get driving signals
 d = driving_function_imp_wfs(x0,xs,src,conf);
+% Fix the time to account for sample offset of the pre-equalization filter
+if usehpre
+ % add a time offset due to the filter (the filter has 128 coefficients,
+ % hence the offset is 64 samples)
+ t = t + 64;
+end
 % Calculate sound field
 [varargout{1:min(nargout,4)}] = ...
  sound_field_imp(X,Y,Z,x0,greens_function,d,t,conf);

SFS_time_domain/wfs_preequalization.m

@@ -78,9 +78,6 @@
  hpre = wfs_fir_prefilter(conf);
  % apply filter
  ir = convolution(hpre,ir);
- % remove time offset due to the filter (the filter has 128 coefficients,
- % hence we can remove 64 samples at the beginning)
- ir = ir(65:end,:);
 elseif strcmp('IIR',hpretype)
  % get IIR filter
  hpre = wfs_iir_prefilter(conf);