function chiResult = fzerosscpt(p,varargin);
% FZEROSSCPT(P,K,D,H1,ETA1,ETA2,R1,R2,RHO1,RHO2,CHITYPE) Function handle
%       used to find zero point of 1/chi(k,p) for bilayer model.
%
% INPUT ARGUMENTS:
%       P (1/s)             : Laplace frequency
%       K (1/nm)            : in-plane wave vector
%       D (nm)              : total film thickness
%       H1 (nm)             : bottom layer thickness
%       ETA1 (kg/(s*nm))    : dyanmic viscosity of bottom layer
%       ETA2 (kg/(s*nm))    : dynamic viscosity of top layer
%       R1 (kg/s^2)         : interface tension
%       R2 (kg/s^2)         : surface tension
%       RHO1 (kg/nm^3)      : mass density of bottom layer
%       RHO2 (kg/nm^3)      : mass density of top layer
%       CHITYPE             : [1,1],[1,2],[2,1],[2,2] specify
%                             susceptibility to be used.
%
% OUTPUT ARGUMENTS:
%       CHIRESULT           : real susceptibility of the surface for
%                             laplace frequency.
%
% See also SSCPTKER

% --- get input arguments
k       = varargin{1};
d       = varargin{2}; 
h1      = varargin{3}; 
eta1    = varargin{4}; 
eta2    = varargin{5}; 
r1      = varargin{6}; 
r2      = varargin{7}; 
rho1    = varargin{8}; 
rho2    = varargin{9};
chiType = varargin{10};

chi      = sscptker(p,k,d,h1,eta1,eta2,r1,r2,rho1,rho2);
chiResult = 1./real(chi(chiType(1),chiType(2)));

return;