#### Description:

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.

Type:

  Integer (boolean), read-only.

#### Applicability

##### Mapping

All Mappings have this attribute.

##### CmpMap

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.

##### Frame

The IsLinear value for a Frame is 1 (since a Frame is equivalent to a UnitMap).

##### FrameSet

The IsLinear value for a FrameSet is obtained from the Mapping from the base Frame to the current Frame.
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