Understanding an equation with multiple Summations

*To*: mathgroup at smc.vnet.net*Subject*: [mg89735] Understanding an equation with multiple Summations*From*: crd319 at gmail.com*Date*: Thu, 19 Jun 2008 05:43:59 -0400 (EDT)

I am working on a project which involves comparing two regions of an image by means of a "G statistic" The equation I am to use is as follows: E_(variable) denotes a Sigma (Summation) with variable as its condition ie: ------- \ / ------- variable s,m are two histograms (256x8 2D histograms) i is a bin number f_i is the frequency at bin i The equation, as defined in the paper I'm using, is: G = 2*( [E_s,m E_i f_i log f_i] -[E_s,m (E_i f_i) log (E_i f_i)] - [E_i (E_s,m f_i) log (E_s,m f_i) ] + [(E_s,m E_i f_i) log (E_s,m E_i f_i) ] I am trying to perform this comparison within a computer program but I am unsure of the logical flow of it, mostly since there are 3 variables (s,m,i) but only one is explicitly shown to be used. I am not familiar with this complex of a problem so if anyone could help my try and decipher this equation, I would be grateful.