l implies
0040 that the set of cross products also includes the original data channels, 
0041 as well as the DC channel.
0042 <span class="comment">%}</span>
0043 
0044 <span class="comment">% append DC channel</span>
0045 x=[x, ones(nsamples,1,ntrials)*mean(abs(x(:)))];
0046 
0047 <span class="comment">% not sure why this makes things better:</span>
0048 <span class="keyword">if</span> 1
0049     THRESH=0;<span class="comment">%10^-12;</span>
0050     [topcs,pwr]=nt_pca0(x,[],[],THRESH); 
0051     x=nt_mma