Subroutine:	IRCO_TOSPHER.

 Purpose:	Transform from rectangular to spherical coordinates.

 Category	WORLD COORDINATES, IRAS

 File:		irco.shl

 Author:	90 Apr 03 Binne Viersen.

 Use:
	call IRCO_TOSPHER (
		xyz	  I	doubleprecision array (3,n),
		lon, lat  O	doubleprecision arrays (n),
		n	  I	integer.
		)
	xyz	  array of rectangular coordinates,
	lon, lat  (in radians:) longitudes and latitudes,
	n 	  number of vectors to be transformed.
 Description:
	This module does the opposite of IRCO_TORECT. A vector of length 
	zero will give a latitude and a longitude of 0.0.
	If x and y are zero then it is a pole and the longitude will be 0.0.
 Updates:
	90 Apr 24 Sjag Steensma; documentation only.