# Understanding equations with multiple summations

Discussion in 'General Math' started by crd319, Jun 18, 2008.

1. ### crd319Guest

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 gratefuk

crd319, Jun 18, 2008

2. ### Frederick WilliamsGuest

Written in which language?
I suggest you ask in comp.lang.<the language in question>.

Frederick Williams, Jun 19, 2008

3. ### crd319Guest

Right now, Im less worried about physical implementation and more just
trying to understand the equation. If I can get the theory, I can
figure out the code.

CHris

crd319, Jun 20, 2008