diff dsp/smooth_with.m @ 32:c3b0cd708782

Imported core dsp tools.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/smooth_with.m	Sun Jan 20 13:48:47 2013 +0000
@@ -0,0 +1,24 @@
+function Z=smooth_with(h,i,Y)
+% smooth_with - Smooth a signal by convolution without changing length
+%
+% smooth_with :: [[M]], 1..M, [[N]] -> [[N]].
+
+m=length(h);
+h=stoch(h(:))';
+csh=cumsum(h);
+rsh=fliplr(cumsum(fliplr(h)));
+
+if isvector(Y), Z=sm(Y);
+else Z=maprows(@sm,Y); 
+end
+
+function z=sm(y)
+	z=conv(h,y); % complete convolution
+	z=z(i:end-(m-i)); % trim the ends
+
+	% rescale end bits
+	z(1:m-i)=z(1:m-i)./csh(i:end-1);
+	z(end-i+2:end)=z(end-i+2:end)./rsh(2:i);
+end
+
+end