% MKHIGHPASS return a high pass filter mfir(). A Butterworth filter is used.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% DESCRIPTION: MKHIGHPASS return a high pass filter mfir().
%              A Butterworth filter is used.
%
% CALL:        f = mkhighpass(f, pl)
%
% VERSION: $Id: mkhighpass.m,v 1.8 2011/04/04 11:37:02 hewitson Exp $
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function f = mkhighpass(f, pl)

  g     = find(pl, 'gain');
  fc    = find(pl, 'fc');
  fs    = find(pl, 'fs');
  order = find(pl, 'order');
  win   = find(pl, 'Win');

  utils.helper.checkFilterOptions(pl);


  f.name     = 'highpass';
  f.fs       = fs;
  f.a        = g.*fir1(order, 2*fc(1)/fs, 'high', win.win);
  f.gd       = (f.ntaps-1)/2;
  f.histout  = zeros(1,f.ntaps-1);   % initialise output history
end