function [a,b,c,d]=wgt1o(vl,vh,fc)
%WGT1O  State space description of a first order weighting function.
%
%       FORMAT:         [a,b,c,d]=wgt1o(vl,vh,fc)
%
%       vl = Gain @ low frequencies
%       vh = Gain @ high frequencies
%       fc = Corner frequency

%       K P Mueller 09-JAN-1993
%       Copyright (c) 1993, by IfR

error(nargchk(3,3,nargin));
error(nargchk(4,4,nargout));
if vl == vh
    a=[];
    b=[];
    c=[];
else
    a=[-2*pi*fc];
    b=[-2*pi*fc];
    c=[vh-vl];
end
d=[vh];
