NAME: 
  gauss2d
 PURPOSE: 
  Compute a two dimensional gaussian within an array.
 DESCRIPTION:
 CATEGORY:
  Mathematical
 CALLING SEQUENCE:
  pro gauss2d,nx,ny,x,y,fwhm,array
 INPUTS:
  nx   - X size of output array
  ny   - Y size of output array
  x    - X location of gaussian in array
  y    - Y location of gaussian in array
  fwhm - Full width at half-maximum of gaussian.
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  array - Result array with gaussian inserted.
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  94/04/07, Written by Marc W. Buie, Lowell Observatory