Stereographic.c File Reference

Routines to perform rotations on the celestial sphere and stereographic projection. More...

Prototypes
void	LALRotatePolarU (LALStatus *status, REAL8UnitPolarCoor *out, REAL8UnitPolarCoor *in, REAL8UnitPolarCoor *par)
void	LALInvRotatePolarU (LALStatus *status, REAL8UnitPolarCoor *out, REAL8UnitPolarCoor *in, REAL8UnitPolarCoor *par)
void	LALStereoProjectPolar (LALStatus *status, REAL8Polar2Coor *out, REAL8UnitPolarCoor *in)
void	LALStereoProjectCart (LALStatus *status, REAL8Cart2Coor *out, REAL8UnitPolarCoor *in)
void	LALStereoInvProjectPolar (LALStatus *status, REAL8UnitPolarCoor *out, REAL8Polar2Coor *in)
void	LALStereoInvProjectCart (LALStatus *status, REAL8UnitPolarCoor *out, REAL8Cart2Coor *in)

Detailed Description

Routines to perform rotations on the celestial sphere and stereographic projection.

Author

Sintes, A. M.

Description

The function LALRotatePolarU() rotates the celestial sphere so that a given point, in the rotated coordinates, corresponds to ( \( \alpha = 0 \) , \( \delta = -\pi/2 \) ). The inputs are: *par the reference point (e.g., the center of the sky-patch) of type REAL8UnitPolarCoor and *in the point on the celestial sphere we want to rotate. The output is *out of type REAL8UnitPolarCoor containing the coordinates of the point in the rotated reference frame.

The function LALInvRotatePolarU() does the inverse rotation. Given the reference point *par (e.g., the center of the sky-patch) of type REAL8UnitPolarCoor and a point *in in the rotated reference frame, the output *out are the coordinates of the point is the same reference system as *par. All inputs and output being of type REAL8UnitPolarCoor.

Given a point on the celestial sphere *in of type REAL8UnitPolarCoor, the function LALStereoProjectPolar() returns *out, of type REAL8Polar2Coor, the stereographic projection of that point in polar coordinates, with the particularity that out->radius can be positive or negative. in->delta= \( \pi/2 \) is an invalid argument and an error will output.

Given a point on the celestial sphere *in of type REAL8UnitPolarCoor, the function LALStereoProjectCart() returns *out, of type REAL8Cart2Coor, the stereographic projection of that point in Cartesian coordinates. in->delta= \( \pi/2 \) is an invalid argument and an error will output.

Given a point on the projected plane *in , the functions LALStereoInvProjectPolar() and LALStereoInvProjectCart() provide the corresponding point on the sphere *out (corresponding to the inverse stereographic projection) of type REAL8UnitPolarCoor.

Definition in file Stereographic.c.

Go to the source code of this file.