www.pudn.com > gmm_utilities.zip > kernel_divide.m

function gr = kernel_divide(g1,g2) 
% 
% gr = g1/g2 
% 
if length(g2.w) == 1 
    gr = kernel_divide_gauss_denominator(g1, g2); 
else 
    gr = kernel_divide_kernel_denominator(g1, g2); 
end 
 
% 
% 
 
function gr = kernel_divide_gauss_denominator(g1, g2) 
D = size(g1.x, 1); 
M = size(g1.x, 2); 
 
gr.w = zeros(1,M); 
gr.x = zeros(D,M); 
 
for i=1:M 
    [gr.x(:,i), gr.P, w] = gauss_divide(g1.x(:,i), g1.P(:,:,i), g2.x, g2.P); 
    gr.w(i) = g1.w * w; 
end 
 
% 
% 
 
function gr = kernel_divide_kernel_denominator(g1, g2) 
warning('Approximate solution'); 
 
% Matt Ridley's division approximation for kernels. 
% See Section 7.5 of his thesis. 
% 
% TODO, look at: 
% - (approximately) factoring gaussian mixtures 
% - the Fast Gauss Transform, does it offer insights? 
% - automatic factoring of polynomials, is this a similar problem?