--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@miir/mkallpass.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,44 @@
+% MKALLPASS returns an allpass filter miir(). 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: MKALLPASS returns an allpass filter miir().
+%
+% CALL:        f = mkallpass(f, pl)
+%
+% VERSION: $Id: mkallpass.m,v 1.2 2010/10/29 16:09:14 ingo Exp $
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+function f = mkallpass(f, pl)
+  
+  fs     = find(pl, 'fs');
+  method = find(pl, 'method');
+  D      = find(pl, 'delay');
+  N      = find(pl, 'N');
+  
+  % Build filter coefficients
+  switch method
+    case 'thirlen'
+      for k=0:N        
+        a(k+1) = (-1.0)^k * factorial(N)/(factorial(k)*factorial(N-k));        
+        for n=0:N
+          a(k+1) = a(k+1) * (D-N+n)/(D-N+k+n);
+        end
+      end
+      
+      a = a/sum(a);
+      b(1) = 1;
+      
+    otherwise
+      error(['Unrecognised method [' method ']']);
+  end
+  
+  % Set filter properties
+  f.name    = 'bandpass';
+  f.fs      = fs;
+  f.a       = a;
+  f.b       = b;
+  f.histin  = zeros(1,f.ntaps-1); % initialise input history
+  f.histout = zeros(1,f.ntaps-1); % initialise output history
+end
+