PRO region_overlap_1d, r1xlo, r1xhi, r2xlo, r2xhi, oxlo, oxhi, status

; Description: This module determines the overlap range between two index ranges in one dimension. 
;              The first index range is defined by "[r1xlo:r1xhi]" and the second index range is 
;              defined by "[r2xlo:r2xhi]". The overlap range is defined by "[oxlo:oxhi]". If the 
;              overlap range is non-empty then "status" is returned with the value "1", otherwise 
;              "status" is returned with the value "0".
;
; Input Parameters:
;
;   r1xlo - INTEGER/LONG - The x index/pixel number of the lower bound of the first range.
;   r1xhi - INTEGER/LONG - The x index/pixel number of the upper bound of the first range. This
;                          parameter must have a value that is greater than or equal to the value
;                          of the parameter "r1xlo".
;   r2xlo - INTEGER/LONG - The x index/pixel number of the lower bound of the second range.
;   r2xhi - INTEGER/LONG - The x index/pixel number of the upper bound of the second range. This
;                          parameter must have a value that is greater than or equal to the value
;                          of the parameter "r2xlo".
;
; Output Parameters:
;
;   oxlo - LONG - The x index/pixel number of the lower bound of the overlap range. This parameter 
;                 is returned with a value of "0" if the overlap range is empty.
;   oxhi - LONG - The x index/pixel number of the upper bound of the overlap range. This parameter 
;                 is returned with a value of "0" if the overlap range is empty.
;   status - INTEGER - This parameter is returned with a value of "1" if the overlap range is 
;                      non-empty, and it is returned with a value of "0" if the overlap range is 
;                      empty.
;
; Author: Dan Bramich (dan.bramich@hotmail.co.uk)
;
; History:
;
;   18/08/2008 - Module created (dmb)

;Check that the input parameters are numbers of the correct type

;Calculate the length of each range

;If the lengths of either range are not sensible, then return with an empty overlap range

;Determine the overlap range

;If an overlap range exists, then set the value of "status" to "1"

;If there is no overlap range, then set the value of "status" to "0" and return an empty overlap range