Merge commit '2f387ff' into release

external/signal/resample.m

@@ -129,8 +129,13 @@
 hpad = [hpad; zeros(nz_post,1)];
 
 % filtering
-xfilt = upfirdn(x,hpad,p,q);
-y = xfilt(offset+1:offset+Ly,:);
+if p==1 && q==1
+  % no resampling needed.
+  y = x;
+else
+  xfilt = upfirdn(x,hpad,p,q);
+  y = xfilt(offset+1:offset+Ly,:);
+end
 
 if isrowvector
   y=y.';

external/signal/upfirdn.m

@@ -39,5 +39,8 @@
 end
 
 yout = upsample(xin,p);
-yout = convn(yout, h); % original was filter(h, 1, yout);
+yout = convn(yout, h).*p; % original was filter(h, 1, yout);
+% the scaling with p is needed as per github issue 2085, causing the output
+% to be scaled by the value of p, with this change, the compat/matlab
+% versions will give an output that is about equal (scaled with about 0.9993)
 yout = downsample(yout,q);

test/test_issue2085.m

@@ -0,0 +1,71 @@
+function test_issue2085
+
+% MEM 1gb
+% WALLTIME 00:10:00
+% DEPENDENCY ft_resampledata ft_specest_irasa
+
+% test function to evaluate the reported scale difference when resampling
+% with the drop in compat replacement of the resample function (and lower
+% level dependencies).
+
+global ft_default
+[ftver, ftpath] = ft_version;
+
+
+% simulate data
+t = (1:1000)/1000;
+fn = cumsum(randn(1,length(t))); 
+in_dat = fn + cos(2*pi*10*t) + cos(2*pi*60*t);
+
+in_dat = in_dat - mean(in_dat);
+
+% resample, using a variety of p/q ratios
+p = [1:50 1:50]; q = [10*ones(1,50) 11*ones(1,50)];
+
+restoredefaultpath
+addpath(ftpath);
+ft_default.toolbox.signal = 'compat';
+ft_defaults;
+fprintf(sprintf('resampling with: %s\n', which('resample')));
+for k = 1:numel(p)
+  out_ft_rspu{k,1} = resample(in_dat, p(k), q(k));
+  out_ft_rspd{k,1} = resample(in_dat, q(k), p(k));
+end
+
+restoredefaultpath
+addpath(ftpath);
+ft_default.toolbox.signal = 'matlab';
+ft_defaults;
+fprintf(sprintf('resampling with: %s\n', which('resample')));
+for k = 1:numel(p)
+  out_mat_rspu{k,1} = resample(in_dat, p(k), q(k));
+  out_mat_rspd{k,1} = resample(in_dat, q(k), p(k));
+end
+
+for k = 1:numel(p)
+  bd(k,1) = out_ft_rspd{k}/out_mat_rspd{k};
+  bu(k,1) = out_ft_rspu{k}/out_mat_rspu{k};
+end
+figure;plot(bu);hold on;plot(bd);
+
+assert(all(bu>0.999) && all(bd>0.999));
+% there's a tiny scale difference between the legacy matlab and the compat
+% version, which could be titrated to be closer to 1, but that would not be
+% based on a mathematically informed choice, so I think we may accept this <0.1% amplitude diff.
+
+
+% figure(); hold on;
+% plot(in_dat, '-b');
+% plot(out_ft_rspu, '-r');
+% plot(out_mat_rspu, '-g');
+% legend({'original data', 'ft resampled', 'mat resampled'});
+% title('upsample')
+% hold off;
+% 
+% figure(); hold on;
+% plot(in_dat, '-b');
+% plot(out_ft_rspd, '-r');
+% plot(out_mat_rspd, '-g');
+% legend({'original data', 'ft resampled', 'mat resampled'});
+% title('downsample');
+% hold off;