IRA_TRANS

Transforms co-ordinate data

Description:

Co-ordinate data are transformed from sky co-ordinates to image co-ordinates, or vice-versa, using the projection information identified by IDA. The direction of the transformation is determined by the argument FORWRD. If any input co-ordinate values are equal to the Starlink " BAD" value (VAL__BADD) then both the output values are set to the bad value.

Invocation

CALL IRA_TRANS( NVAL, IN1, IN2, FORWRD, SCS, IDA, OUT1, OUT2, STATUS )

Arguments

NVAL = INTEGER (Given)
The number of co-ordinate points to be transformed.
IN1( NVAL ) = DOUBLE PRECISION (Given)
If FORWRD is true, then IN1 holds values of the first image co-ordinate (X), otherwise IN1 holds values of the sky longitude.
IN2( NVAL ) = DOUBLE PRECISION (Given)
If FORWRD is true, then IN2 holds values of the second image co-ordinate (Y), otherwise IN2 holds values of the sky latitude.
FORWRD = LOGICAL (Given)
If true then the forward mapping is used from image co-ordinate to sky co-ordinate. Otherwise, the inverse mapping from sky co-ordinate to image co-ordinates is used.
SCS = CHARACTER ∗ ( ∗ ) (Given)
The name of the sky co-ordinate system in which sky co-ordinates are required (if FORWRD is true), or supplied (if FORWRD is false). Any unambiguous abbreviation will do. This need not be the same as the SCS identified by IDA. See ID2 section " Sky Coordinates" for more information on Sky Co-ordinate Systems. A blank value will cause the system associated with IDA to be used.
IDA = INTEGER (Given)
The IRA identifier for the astrometry information.
OUT1( NVAL ) = DOUBLE PRECISION (Returned)
If FORWRD is true, then OUT1 holds values of the sky longitude corresponding to the image co-ordinates given in arrays IN1 and IN2. Otherwise, OUT1 holds values of the first image co-ordinate (X) corresponding to the input sky co-ordinates.
OUT2( NVAL ) = DOUBLE PRECISION (Returned)
If FORWRD is true, then OUT2 holds values of the sky latitude corresponding to the image co-ordinates given in arrays IN1 and IN2. Otherwise, OUT2 holds values of the second image co-ordinate (Y) corresponding to the input sky co-ordinates.
STATUS = INTEGER (Given and Returned)
The global status.