NAME:
  asteval
 PURPOSE:
  Evaulate an astrometric polynomial function.
 DESCRIPTION:

 CATEGORY:
  Astrometry
 CALLING SEQUENCE:
  val=asteval,ind,coeff,terms
 INPUTS:
  x     - X - coordinate (scalar or vector)
  y     - Y - coordinate (scalar or vector)
  coeff - Coefficients of the transformation, this must be a vector that has
              the terms to be used, the length must be equal to total(terms)
  terms - Which terms are to be used
           This must be a 10 element vector, a 1 means use the term, 0 means don't
              0 - const (always use this)
              1 - x     (always use this)
              2 - y     (always use this)
              3 - r
              4 - x^2
              5 - y^2
              6 - x^3
              7 - y^3
              8 - xy^2
              9 - yx^2

 OPTIONAL INPUT PARAMETERS:

 KEYWORD INPUT PARAMETERS:

 OUTPUTS:
  return value - Dependent value(s), if x,y was 1-d then this will be scalar.

 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  97/06/17, Written by Marc W. Buie, Lowell Observatory