;+
; NAME:
;   JPLEPHTEST
;
; AUTHOR:
;   Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
;   craigm@lheamail.gsfc.nasa.gov
;   UPDATED VERSIONs can be found on my WEB PAGE: 
;      http://cow.physics.wisc.edu/~craigm/idl/idl.html
;
; PURPOSE:
;   Test JPLEPHTEST with JPL test data set
;
; MAJOR TOPICS:
;   Planetary Orbits, Interpolation
;
; CALLING SEQUENCE:
;   JPLEPHTEST, EPHFILE, TESTFILE
;
; DESCRIPTION:
;
;   JPLEPHTEST tests the JPLEPHINTERP procedure for precision.  In
;   order to function, you must have the JPLEPHREAD and JPLEPHINTERP
;   procedures, as well as the IDL Astronomy Libary for reading FITS
;   files.  In addition, you must have a JPL ephemeris test data set,
;   which is available by FTP.
;
;   The procedure opens and reads the test set, which contains
;   precomputed data.  Every tenth value is printed on the screen.
;   Any deviations that exceed 1.5d-13 AU = 1.5 cm are reported.
;
;   The columns are labelled according to the input file, except for
;   the final column, which is the deviation between the input file
;   and the computed value.
;
;
; PARAMETERS: 
;
;   EPHFILE - a scalar string, specifies the name of the ephemeris
;             file, in FITS format.
;
;   TESTFILE - a scalar string, specifies JPL test data set to compare
;              against.
;
;   THRESHOLD - threshold (cm) above which deviations are reported as
;               too large.
;
;
; EXAMPLE:
;
;   Test JPL DE200 and DE405 ephemerides.  Assumes files are in the
;   current directory.
;
;   JPLEPHTEST, 'JPLEPH.200', 'testpo.200'
;   JPLEPHTEST, 'JPLEPH.405', 'testpo.405'
;     
;
; REFERENCES:
;
;   JPL Export Ephmeris FTP Site
;      ftp://navigator.jpl.nasa.gov/pub/ephem/export/
;      (see test-data/ for test data sets)
;   
;   HORIZONS, JPL Web-based ephermis calculator (Ephemeris DE406)
;      http://ssd.jpl.nasa.gov/horizons.html
;
;
; SEE ALSO
;   JPLEPHREAD, JPLEPHINTERP, JPLEPHTEST
;   
; MODIFICATION HISTORY:
;   Written and Documented, CM, Jun 2001
;   Removed TRANSREAD, improved output, improved docs, CM, 9 Jul 2001
;   Add THRESHOLD keyword, CM, 30 Jan 2005
;
;  $Id: jplephtest.pro,v 1.5 2005/01/31 04:20:50 craigm Exp $
;
;-
; Copyright (C) 2001, Craig Markwardt
; This software is provided as is without any warranty whatsoever.
; Permission to use, copy and distribute unmodified copies for
; non-commercial purposes, and to modify and use for personal or
; internal use, is granted.  All other rights are reserved.
;-