$$
{\chi}^2 = { {({\rm mag}(x, y, s) - {\rm mean\_mag}(s) + CF(x, y))^2  } \over
              { \sigma(s)^2 } }
$$


$$
\eqalign {
M &= m \thinspace + a \cr
M &= m \thinspace + \thinspace a_i \cr
M &= m \thinspace + \thinspace a_i \thinspace + \thinspace  b_j ({\rm color}) \cr
M &= m \thinspace + \thinspace a_i \thinspace + \thinspace  b_{1j} ({\rm color}) \thinspace + \thinspace b_{2j} \theta ({\rm color}) \cr
}
$$

$$
M = m \thinspace + \thinspace a_i \thinspace + \thinspace  b_{1j} ({\rm color}) \thinspace + \thinspace b_{2j} \theta ({\rm color}) 
$$

$$
  + \thinspace p_{1i} ({\rm row })  \thinspace
  + \thinspace p_{2i} ({\rm row})^2 \thinspace
  + \thinspace p_{3i} ({\rm col }) \thinspace 
  + \thinspace p_{4i} ({\rm col})^2
$$

$$\eqalign{
M &= m \thinspace + \thinspace a_i \thinspace + \thinspace  b_{1j} ({\rm color}) \thinspace + \thinspace b_{2j} \theta ({\rm color})  \cr
  & + \thinspace p_{1i} ({\rm row })  \thinspace
  + \thinspace p_{2i} ({\rm row})^2 \thinspace
  + \thinspace p_{3i} ({\rm col }) \thinspace 
  + \thinspace p_{4i} ({\rm col})^2 \cr
}
$$




\bye
