diff dsp/specbasis.m @ 33:5b7d90b6393a

Minor tweaks, still needs work.

--- a/dsp/specbasis.m	Sun Jan 20 13:48:47 2013 +0000
+++ b/dsp/specbasis.m	Sun Jan 20 18:56:19 2013 +0000
@@ -1,14 +1,14 @@
 function map=specbasis(edges,M)
 % specbasis - Create frequency mapping matrix
-% 
-% Converts a filterbank specification into a sparse matrix for
-% mutliplying with a linear-frequency spectrogram.
 %
 % as_fmap ::
 %    [[L-1]]    ~ 'array of L-1 bin edge frequencies, in FT bins',
 %    M:natural  ~ 'number of bins in linear-freq spectrum'
 % ->
 %    [[L,M]]    ~ 'L-by-M sparse array'.
+% 
+% Converts a filterbank specification into a sparse matrix for
+% mutliplying with a linear-frequency spectrogram.
 %
 % Note, frequencies must measured in bins of the target spectrum,
 % Also, the first and last of the L bands are catch-alls which
@@ -16,23 +16,11 @@
 % respectively. If, eg, the bottom edge is 0, then the bottom
 % band will be empty.
 
-% 2005-01-15 Written - Samer Abdallah: to reproduce behaviour of
-%          a the function as_fmap_orig.m. It runs at about half
-%          the speed, but this version is only 8 lines of code!
-%          Also, this version doesn't barf if more than one band 
-%          edge falls in a frequency bin.
-%
-% 2005-01-29 SA: switched to measuring frequency in bins and specifying
-%          the size of the spectrum to be remapped. This makes the
-%          function more general in that it doesn't assume that
-%          1+N/2 bins are retained from an N-point FFT. In fact, the
-%          function is now independent of the FFT size.
-
-	E=repmat([0; edges(:); M-1],1,M);
-	I=repmat(0:M-1,length(edges)+1,1);
-	map=sparse(phi(E(2:end,:)-I)-phi(E(1:end-1,:)-I));
-	map=map.*(map>8e-15); % squeeze out more small values
-	map(:,2:end-1)=map(:,2:end-1)/2; % make up for top and bottom bins
+E=repmat([0; edges(:); M-1],1,M);
+I=repmat(0:M-1,length(edges)+1,1);
+map=sparse(phi(E(2:end,:)-I)-phi(E(1:end-1,:)-I));
+map=map.*(map>8e-15); % squeeze out more small values
+map(:,2:end-1)=map(:,2:end-1)/2; % make up for top and bottom bins
 
 %                                     ____
 % this is piecewise linear ramp : ___/