Re: Mixture of Gaussian Integral

From: Robert Israel (israel_at_math.ubc.ca)
Date: 06/07/04


Date: Mon, 7 Jun 2004 11:04:37 -0700 (PDT)

In article <KEWwc.1282$GB4.41814@news.xtra.co.nz>,
Zeke Chan <zekechan@amonics.com> wrote:
>Hi I have a prob here I hope you can help. Let N_a(x) denote Gaussian
>distribution with mean mu_a and cov_a (the subscript indicates the index of
>the distribution). Given a mixture of two gaussians distribution,
>p(b)N_b(x) + p(c)N_c(x), I'd like to the integral
>
>int[ N_a(x) log(p(b) N_b(x) + p(c)N_c(x)) , dx]
>
>Matlab can't solve this. Very grateful if you can find at least an
>approximation to this problem.

Perhaps some clarifications might be helpful. By N_a(x) do you mean the
density of a (one-variable) Gaussian distribution? And are you
integrating from -infinity to infinity?

I doubt that there's a closed-form formula for the answer. If you want
an approximation, useful asymptotic results may be possible. But
you'd need to tell us which parameters are to be considered
small (-> 0) or large (-> infinity).

Robert Israel israel@math.ubc.ca
Department of Mathematics http://www.math.ubc.ca/~israel
University of British Columbia
Vancouver, BC, Canada V6T 1Z2



Relevant Pages

  • Re: Limiting case of an exponential distribution
    ... or infinity, and then once you do that you'll observe a Gaussian? ... said to approach a normal distribution. ... will be less than zero. ... Now suppose you want to approach a standard Gaussian distribution of mean zero, ...
    (comp.soft-sys.matlab)
  • Re: marching cubes help
    ... and concise question to which you expect a clear and concise ... I mean that the distribution is radially symmetric about its ... of Gaussian blurring of a 3D voxel image. ... leading to a large number of small connected components of triangles. ...
    (comp.graphics.algorithms)
  • Re: Transforming a sparse histogram to a Gaussian histogram
    ... distribution) to an image with a Gaussian histogram distribution. ... comprised by all the gray levels 195-200 and the other step has gray ...
    (sci.image.processing)
  • Re: Add Noise
    ... >But by the central limit theorem, it approaches Gaussian as N ... >approaches infinity. ... The variance of the common uniform is 1/12 so the sum of 12 of them ... It is a workable approximation at 1:00 ...
    (comp.lang.fortran)
  • Re: Transforming a sparse histogram to a Gaussian histogram
    ... restoration which uses a Gaussian distribution. ... you're trying an algorithm on image restoration. ... the degraded images have a Gaussian histogram. ...
    (sci.image.processing)