Subroutine: irco_deproject
Purpose: Reconstructs celestial sphere from plane projection.
Category: IRAS
File: irco_deproject.c
Author: Fred Lahuis
Use:
CALL IRCO_DEPROJECT(
PRID, I integer,
X, Y, I double precision array(N),
XYZ, O double precision array(3*N),
N) I integer.
PRID a projection system number (see IRCO_PRNAME),
X, Y the coordinates on the plane,
XYZ corresponding coordinates on the sphere,
N number of coordinates to be deprojected.
This subroutine is the opposite of IRCO_PROJECT.
See IRCO_PROJECT for common properties of the projection methods.
Note that at the edge effects may cause loss of accuracy,
and that maps that are finite (e.g. azimuthal equal-area proj.)
may behave funny when points beyond the edge are de-projected.
However, it is guaranteed that any point in the plane will
be de-projected onto a point of the unit sphere.
Projections where the formulae lend themselves to a periodic
representation (e.g.cylindrical) will use this periodicity,
otherwise points outside the map will be moved to the map edge.
References: IRCO_PRNAME, IRCO_PROJECT.
Updates: 91 Dec 16 Fred Lahuis, Creation date
Original: PRUNPR