	REAL FUNCTION AXIS_DISTANCE ( lo_val, hi_val, idim, grid )

*
*
*  This software was developed by the Thermal Modeling and Analysis
*  Project(TMAP) of the National Oceanographic and Atmospheric
*  Administration's (NOAA) Pacific Marine Environmental Lab(PMEL),
*  hereafter referred to as NOAA/PMEL/TMAP.
*
*  Access and use of this software shall impose the following
*  obligations and understandings on the user. The user is granted the
*  right, without any fee or cost, to use, copy, modify, alter, enhance
*  and distribute this software, and any derivative works thereof, and
*  its supporting documentation for any purpose whatsoever, provided
*  that this entire notice appears in all copies of the software,
*  derivative works and supporting documentation.  Further, the user
*  agrees to credit NOAA/PMEL/TMAP in any publications that result from
*  the use of this software or in any product that includes this
*  software. The names TMAP, NOAA and/or PMEL, however, may not be used
*  in any advertising or publicity to endorse or promote any products
*  or commercial entity unless specific written permission is obtained
*  from NOAA/PMEL/TMAP. The user also understands that NOAA/PMEL/TMAP
*  is not obligated to provide the user with any support, consulting,
*  training or assistance of any kind with regard to the use, operation
*  and performance of this software nor to provide the user with any
*  updates, revisions, new versions or "bug fixes".
*
*  THIS SOFTWARE IS PROVIDED BY NOAA/PMEL/TMAP "AS IS" AND ANY EXPRESS
*  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*  ARE DISCLAIMED. IN NO EVENT SHALL NOAA/PMEL/TMAP BE LIABLE FOR ANY SPECIAL,
*  INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
*  RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
*  CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION, ARISING OUT OF OR IN
*  CONNECTION WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE. 
*
*
* compute the length of axis between the low and high limits given 
* converted to uniform units ( m ) in x, y and z

* programmer - steve hankin
* NOAA/PMEL, Seattle, WA - Tropical Modeling and Analysis Program
* written for VAX computer under VMS operating system
*
* revision 0.0 - 1/12/87
* revision 0.1 - 6/3/87  - changed km --> m as standard unit
* revision 0.2 - 4/18/88 - passed grid to get unit conversion factor
*       *acm* 3/12 cleanup ifdefs and unnecessary include files

	include 'tmap_dims.parm'
	include	'xtm_grid.cmn_text'
	external xgt_grid_data
	include	'xunits.cmn_text'
	external xunits_data
	include	'ferret.parm'

* calling argument declarations:
	REAL*8	lo_val, hi_val
	INTEGER	idim, grid

* internal variable declarations:
	INTEGER	line, un

* simplest length
	AXIS_DISTANCE = hi_val - lo_val

* convert to uniform units
	line = grid_line(idim,grid)
	un   = line_unit_code(line)
	AXIS_DISTANCE = AXIS_DISTANCE * un_convert( un )

	RETURN
	END
