% GETDC get the DC gain factor for a pole-zero model%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% DESCRIPTION% % A zpk model in matlab notation is an object of the type:% % (s-z1)...(s-zN)% zpk = k*----------------% (s-p1)...(s-pn)% % the zero-frequency-gain (zfg) or DC gain of this object is obtained by% the equation, for s = 0.% LTPDA pzmodels are constructed by poles, zeros and DC gain. This means% that the value stored in the 'gain' field of the model is the dc gain!% This function calculate k.% % CALL:% % dc = getdc(z,p,k)% % INPUT:% % z: zeros% p: poles% k: gain coefficient% % % OUTPUT:% % dc: dc gain of the model % % NOTE:% % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% VERSION: $Id: getdc.m,v 1.2 2010/02/22 15:14:17 luigi Exp $%% HISTORY: 08-10-2008 L Ferraioli% Creation%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%function dc = getdc(z,p,k)zrs = prod(-1*z);pls = prod(-1*p);dc = k*zrs/pls;end