www.gusucode.com > signal 工具箱matlab源码程序 > signal/@dfilt/@dtfiir/iirxform.m

    function [Ht, anum, aden] = iirxform(Ho,fun,varargin)
%IIRXFORM IIR Transformations

%   Author(s): J. Schickler
%   Copyright 1988-2004 The MathWorks, Inc.

% This should be private

[b, a] = tf(reffilter(Ho));

[num, den, anum, aden] = feval(fun, b, a, varargin{:});

% Create the transformed filter
Ht = copy(Ho);
arith = Ht.Arithmetic; % Cache setting
Ht.Arithmetic = 'double';
Ht.Numerator = num;
Ht.Denominator = den;
Ht.Arithmetic = arith; % Reset arithmetic

% [EOF]