This attribute indicates whether a
Mapping is an
instance of a class that always represents a linear transformation. Note, some Mapping classes
can represent linear or non-linear transformations (the
MathMap class for instance). Such
classes have a zero value for the IsLinear attribute. Specific instances of such classes can be
tested for linearity using the astLinearApprox function.
AST_LINEARAPPROX routine.
Mapping
All Mappings have this
attribute.
The IsLinear value for a CmpMap is determined by the classes of
the encapsulated Mappings. For instance, a CmpMap that combines a
ZoomMap and a
ShiftMap will have a non-zero value for its IsLinear attribute, but a CmpMap that contains a
MathMap will have a value of zero for its IsLinear attribute.
The IsLinear value for a
Frame is 1 (since a Frame is equivalent to a
UnitMap).
The IsLinear value for
a FrameSet is obtained from the Mapping from the base Frame to the current Frame.