Subroutine:	IRCO_TORECT.

 Purpose:	Transform from spherical to rectangular coordinates.

 Category	WORLD COORDINATES, IRAS

 File:		irco.shl

 Author:	85 Jul 17 Uwe Peppel.

 Use:
	call IRCO_TORECT (
		lon, lat  I	doubleprecision arrays (n),
		xyz	  O	doubleprecision array (3,n),
		n 	  I	integer.
		)
	lon, lat (in radian:) longitudes and latitudes,
	xyz	 rectangular coordinates,
	n	 number of coordinates to transform.
 Description:
	Transformation according to:
		x = cos(lat) * cos(lon),
 		y = cos(lat) * sin(lon),
		z = sin(lat).
	In this module (psi, theta) is not applicable, use:
	call IRCO_TORECT ( psi, pi/2 - theta, xyz, n) !!
 Updates:
	90 Apr 24 Sjag Steensma; documentation changed, n-coordinates,
	87 May 25 Timo Prusti; unification of versions,
	87 May 25 Romke Bontekoe; documentation changed.