--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@miir/mklowpass.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,33 @@
+% MKLOWPASS return a low pass filter miir(). A Butterworth filter is used.
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: MKLOWPASS return a low pass filter miir().
+%              A Butterworth filter is used.
+%
+% CALL:        f = mklowpass(f, pl)
+%
+% VERSION: $Id: mklowpass.m,v 1.10 2011/04/04 11:37:02 hewitson Exp $
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+function f = mklowpass(f, pl)
+
+  g     = find(pl, 'gain');
+  fc    = find(pl, 'fc');
+  fs    = find(pl, 'fs');
+  order = find(pl, 'order');
+
+  utils.helper.checkFilterOptions(pl);
+
+  % Build coefficients
+  [a, b] = butter(order, 2*fc(1)/fs);
+
+  % Set filter properties
+  f.name    = 'lowpass';
+  f.fs      = fs;
+  f.a       = a.*g;
+  f.b       = b;
+  f.histin  = zeros(1,f.ntaps-1); % initialise input history
+  f.histout = zeros(1,f.ntaps-1); % initialise output history
+end
+