dynare/matlab/recursive_moments.m

38 lines
1.1 KiB
Matlab

function [mu,sigma,offset] = recursive_moments(m0,s0,data,offset)
% Recursive estimation of order one and two moments (expectation and
% covariance matrix).
%
% INPUTS
% o m0 [double] (n*1) vector, the prior expectation.
% o s0 [double] (n*n) matrix, the prior covariance matrix.
% o data [double] (T*n) matrix.
% o offset [integer] scalar, number of observation previously
% used to compute m0 and s0.
% OUTPUTS
% o mu [double] (n*1) vector, the posterior expectation.
% o sigma [double] (n*n) matrix, the posterior covariance matrix.
% o offset [integer] = offset + T.
%
% ALGORITHM
% None.
%
% SPECIAL REQUIREMENTS
% None.
%
% part of DYNARE, copyright dynare Team (2006-2008)
% Gnu Public License.
[T,n] = size(data);
for t = 1:T
tt = t+offset;
m1 = m0 + (data(t,:)'-m0)/tt;
qq = m1*m1';
s1 = s0 + ( (data(t,:)'*data(t,:)-qq-s0) + (tt-1)*(m0*m0'-qq') )/tt;
m0 = m1;
s0 = s1;
end
mu = m1;
sigma = s1;
offset = offset+T;