SURFLIB_CALC_DUAL_BEAM - Calculates a chopped map from a single beam map

Description:

This routine can be used to added a chopped beam response to a single beam image. When NBEAMS=2 this routine calculates a middle-beam dual-beam map by calculating the difference between the left and right beams for each pixel in the map.

When NBEAMS=3 a triple beam map is constructed where the central beam is the difference between the central beam and the average of the positions a chop distance away on either side.

All pixels off the edge of the image are assumed to have flux 0 and variance 0.

Bad pixels are assumed to be equivalent to flux of 0 and variance 0, although for the triple beam image a bad pixel is retained if it coincide with the middle beam position.

Invocation:

CALL SURFLIB_CALC_CHOPPED_IMAGE( NBEAMS, CHOP_THR, CHOP_PA, DIM1, DIM2, IN_DATA, OUT_DATA, USEVAR, IN_VAR, OUT_VAR, STATUS)

Arguments:

NBEAMS = INTEGER (Given)

Number of beams to add. (2 or 3)

CHOP_THR = REAL (Given)

Chop throw in pixels

CHOP_PA = REAL (Given)

Chop position angle (east of north) in degrees

DIM1 = INTEGER (Given)

First dimension of image

DIM2 = INTEGER (Given)

Second dimension of image [can not use DIMS as an array since the linux fortran compiler doesnt like it]

IN_DATA = REAL (Given)

Input single-beam image

OUT_DATA = REAL (Returned)

Output dual-beam image

USEVAR = LOGICAL (Given)

Are we processing a variance array?

IN_VAR = REAL (Given)

Input variance image (if USEVAR=TRUE)

OUT_VAR = REAL (Returned)

Output variance image (if USEVAR=TRUE)

STATUS = INTEGER (Given and Returned)

Global status

Copyright

Copyright ©1995,1996,1997,1998,1999 Particle Physics and Astronomy Research Council. All Rights Reserved.