NAME: 
  rotpoint
 PURPOSE: 
  Rotate x,y,z point(s) about arbitrary axis.
 DESCRIPTION:
 CATEGORY:
  Mathematical
 CALLING SEQUENCE:
  rotpoint,x,y,z,axis,angle,xp,yp,zp
 INPUTS:
  x     - Cartesian x-coordinate of point.
  y     - Cartesian y-coordinate of point.
  z     - Cartesian z-coordinate of point.
  axis  - Axis to rotate about:
           'x' or 'X' or 0  - indicates rotation about x-axis
           'y' or 'Y' or 1  - indicates rotation about y-axis
           'z' or 'Z' or 2  - indicates rotation about z-axis
  angle - Angle to rotate by (scalar).  Radians unless /DEG is set.
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
  DEG - flag, if true indicates angle is in degrees, otherwise angle is
           taken to be in radians.
 OUTPUTS:
  xp - Rotated x-coordinates.
  yp - Rotated y-coordinates.
  zp - Rotated z-coordinates.
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  Written 1/4/95 by Marc W. Buie, Lowell Observatory