’s forward transformation, followed immediately by the matching inverse transformation will always restore the original set of coordinates. It indicates that AST may replace such a sequence of operations by an identity Mapping (a UnitMap) if it is encountered while simplifying a compound Mapping (e.g. using AST_SIMPLIFY).
By default, the SimpFI attribute is zero, so that AST will not perform this simplification unless you have set SimpFI to indicate that it is safe to do so.
For simplification to occur, the two MathMaps must be in series and be identical (with textually identical transformation functions). Functional equivalence is not sufficient.
The consent of both MathMaps is required before simplification can take place. If either has a SimpFI value of zero, then simplification will not occur.
The SimpFI attribute controls simplification only in the case where a MathMap
’ s forward
transformation is followed by the matching inverse transformation. It does not apply if an inverse
transformation is followed by a forward transformation. This latter case is controlled by the SimpIF
" transformations referred to are those defined when the MathMap is
created (corresponding to the FWD and INV arguments of its constructor function). If the MathMap is
inverted (i.e. its Invert attribute is non-zero), then the role of the SimpFI and SimpIF attributes will be