function sim = model_match_models(model1, model2)
% sim = model_match_models(model1, model2)
%    Return a distance between two models
% 2007-04-30 dpwe@ee.columbia.edu

if (model1.nmix > 1) | (model2.nmix > 2)
  error('model_match_models only for single gauss at present');
else
  % KL distance between single Gausses
  dmean = model1.mean - model2.mean;
  ndim = length(dmean);
  kl2 = dmean'*(model1.invsigma + model2.invsigma)*dmean ...
        + trace(model1.sigma*model2.invsigma + model2.sigma*model1.invsigma) ...
        - 2*ndim;
  % make it larger = more similar, KL = 0 -> sim = 1
  sim = 1/(1+kl2);
end