evaluateAlphaBetaParam(process, noisy, dt)

function [alpha, beta] = evaluateAlphaBetaParam(process, noisy, dt)
% evaluateAlphaBetaParam - evaluates alpha and beta parameters for alpha-beta filter
% With this parameters, alpha-beta filter becomes a steady-state Kalman filter
%
% Syntax:  [xkp,vkp] = alphaBetaFilter(xm, dt, xk, vk, alpha, beta)
%
% Inputs:
%   process - real system state
%     noisy - measured system state
%
% Outputs:
%   alpha - alpha parameter
%    beta - beta parameter
%
% Other m-files required: none
% Subfunctions: none
% MAT-files required: none
%
% See also: alphaBetaFilter;

% Author: Marco Borges, Ph.D. Student, Computer/Biomedical Engineer
% UFMG, PPGEE, Neurodinamica Lab, Brazil
% email address: [e-mail]
% Website: http://www.cpdee.ufmg.br/
% June 2013; Version: v1; Last revision: 2013-06-27
% Changelog:
% 
%------------------------------- BEGIN CODE -------------------------------
varProcess = var(process);
varNoise = var(noisy);
l = varProcess * dt / varNoise; % lambda
r = (4+l-sqrt(8*l+l^2))/4;
alpha = 1 - r^2;
beta = 2*(2-alpha)-4*sqrt(1-alpha);
end
%-------------------------------- END CODE --------------------------------