什么是 associativity ???

SANYAN68

Setting Principal Axis and Orientation

The definition of the coordinate system involves two vectors, the Principal Axis vector and the Orientation About Principal Axis vector. The coordinate system respects the plane formed by these two vectors and aligns with the Principal Axis. Use the Principal Axis category in the Details view to define one of either the X, Y, or Z axes in terms of a:

． Geometry Selection - Associatively align axis to a topological feature in the model. When a change occurs to the feature, the axis automatically updates to reflect the change.

． Fixed Vector – Depending upon the Geometry Selection, this option preserves the current Geometry Selection without associativity. When a change occurs to the feature the axis will not update automatically to reflect that change.

． Global X, Y, Z axis – Force the axis to align to a global X, Y, or Z axis.

Use the Orientation About Principal Axis category in the Details view to define one of the orientation X, Y, or Z axes in terms of the Default, Geometry Selection, the Global X, Y, Z axes, or Fixed Vector.
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什么是 associativity ???

SANYAN68

关联性( associativity)

指的是在数学中一些二进制运算的所有物吗?

http://en.wikipedia.org/wiki/Associativity