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AST_AXOFFSET - Add an increment onto a supplied axis value

Description:
This routine returns an axis value formed by adding a signed axis increment onto a supplied axis value.

For a simple Frame, this is a trivial operation returning the sum of the two supplied values. But for other derived classes of Frame (such as a SkyFrame) this is not the case.

Invocation:
RESULT = AST_AXOFFSET( THIS, AXIS, V1, DIST, STATUS )
Arguments:
THIS = INTEGER (Given)
Pointer to the Frame.
AXIS = INTEGER (Given)
The index of the axis to which the supplied values refer. The first axis has index 1.
V1 = DOUBLE PRECISION (Given)
The original axis value.
DIST = DOUBLE PRECISION (Given)
The axis increment to add to the original axis value.
STATUS = INTEGER (Given and Returned)
The global status.
Returned Value:
AST_AXOFFSET = DOUBLE PRECISION
The incremented axis value.
Notes:
  • This function will return a "bad" result value (AST__BAD) if any of the input values has this value.

  • A "bad" value will also be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.


next up previous 264
Next: AST_BBUF - Begin a new graphical buffering context
Up: AST Routine Descriptions
Previous: AST_AXDISTANCE - Find the distance between two axis values

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council