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TranForward - Forward transformation defined?

Description:
This attribute indicates whether a Mapping is able to transform coordinates in the "forward" direction (i.e. converting input coordinates into output coordinates). If this attribute is non-zero, the forward transformation is available. Otherwise, it is not.
Type:
Integer (boolean), read-only.
Class Applicability:
Mapping
All Mappings have this attribute.
CmpMap
The TranForward attribute value for a CmpMap is given by the boolean AND of the value for each component Mapping.
FrameSet
The TranForward attribute of a FrameSet applies to the transformation which converts between the FrameSet's base Frame and its current Frame (as specified by the Base and Current attributes). This value is given by the boolean AND of the TranForward values which apply to each of the individual sub-Mappings required to perform this conversion. The TranForward attribute value for a FrameSet may therefore change if a new Base or Current Frame is selected.
Notes:
  • An error will result if a Mapping with a TranForward value of zero is used to transform coordinates in the forward direction.


next up previous 264
Next: TranInverse - Inverse transformation defined?
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AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council