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PolyMap - Map coordinates using polynomial functions

Description:
A PolyMap is a form of Mapping which performs a general polynomial transformation. Each output coordinate is a polynomial function of all the input coordinates. The coefficients are specified separately for each output coordinate. The forward and inverse transformations are defined independantly by separate sets of coefficients. If no inverse transformation is supplied, an iterative method can be used to evaluate the inverse based only on the forward transformation.
Constructor Function:
astPolyMap
Inheritance
The PolyMap class inherits from the Mapping class.
Attributes
In addition to those attributes common to all Mappings, every PolyMap also has the following attributes:

  • IterInverse: Provide an iterative inverse transformation?

  • NiterInverse: Maximum number of iterations for iterative inverse

  • TolInverse: Target relative error for iterative inverse
Functions
In addition to those functions applicable to all Objects, the following functions may also be applied to all Mappings:

  • astPolyTran: Fit a PolyMap inverse or forward transformation


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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
25th February 2013
E-mail:starlink@jiscmail.ac.uk

Copyright (C) 2014 Science \& Technology Facilities Council