NAME: 
  num_size
 PURPOSE:   (one line only)
  Gives the relative number vs. diameter of craters
 DESCRIPTION:
  This is an approximation of the number of craters as a function of
  size.  The function is a power law and is intended to
  represent a simple distribution of asteroids.
  This function is meant to be probabalistically sampled with smplprb.pro.
 CATEGORY:
  Miscellaneous
 CALLING SEQUENCE:
  array=num_size(m)
 INPUTS:
  m      :Vector or scalar of crater diameters (units do not matter)
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
  array  :Returns an array of the same size as m.
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  2004/07/13, Written by Maureen Teyssier, REU Lowell Observatory
  2004/07/15, MWB, incorporated into library.
  2022/03/07, MWB, cloned from num_mag.pro