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Mapping - Inter-relate two coordinate systems

Description:
This class provides the basic facilities for transforming a set of coordinates (representing "input" points) to give a new set of coordinates (representing "output" points). It is used to describe the relationship which exists between two different coordinate systems and to implement operations which make use of this (such as transforming coordinates and resampling grids of data). However, the Mapping class does not have a constructor function of its own, as it is simply a container class for a family of specialised Mappings which implement particular types of coordinate transformation.
Constructor Function:
None.
Inheritance
The Mapping class inherits from the Object class.
Attributes
In addition to those attributes common to all Objects, every Mapping also has the following attributes:

  • Invert: Mapping inversion flag

  • IsLinear: Is the Mapping linear?

  • IsSimple: Has the Mapping been simplified?

  • Nin: Number of input coordinates for a Mapping

  • Nout: Number of output coordinates for a Mapping

  • Report: Report transformed coordinates?

  • TranForward: Forward transformation defined?

  • TranInverse: Inverse transformation defined?
Functions
In addition to those functions applicable to all Objects, the following functions may also be applied to all Mappings:



next up previous 264
Next: MathMap - Transform coordinates using mathematical expressions
Up: AST Class Descriptions
Previous: LutMap - Transform 1-dimensional coordinates using a lookup table

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