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−% MKALLPASS returns an allpass filter miir(). 
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−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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−%
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−% DESCRIPTION: MKALLPASS returns an allpass filter miir().
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−%
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−% CALL:        f = mkallpass(f, pl)
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−%
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−% VERSION: $Id: mkallpass.m,v 1.2 2010/10/29 16:09:14 ingo Exp $
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−%
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−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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−
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−function f = mkallpass(f, pl)
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−  
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−  fs     = find(pl, 'fs');
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−  method = find(pl, 'method');
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−  D      = find(pl, 'delay');
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−  N      = find(pl, 'N');
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−  
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−  % Build filter coefficients
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−  switch method
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−    case 'thirlen'
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−      for k=0:N        
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−        a(k+1) = (-1.0)^k * factorial(N)/(factorial(k)*factorial(N-k));        
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−        for n=0:N
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−          a(k+1) = a(k+1) * (D-N+n)/(D-N+k+n);
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−        end
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−      end
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−      
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−      a = a/sum(a);
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−      b(1) = 1;
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−      
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−    otherwise
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−      error(['Unrecognised method [' method ']']);
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−  end
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−  
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−  % Set filter properties
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−  f.name    = 'bandpass';
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−  f.fs      = fs;
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−  f.a       = a;
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−  f.b       = b;
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−  f.histin  = zeros(1,f.ntaps-1); % initialise input history
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−  f.histout = zeros(1,f.ntaps-1); % initialise output history
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−end
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−