#### Parameters

*sx*- Scale X factor. Factor must be 0 or greater. Values greater than 1 creates a larger envelope, and less then 1 shrinks it.
*sy*- Scale Y factor. Factor must be 0 or greater. Values greater than 1 creates a larger envelope, and less then 1 shrinks it.
*asRatio*- If asRatio = TRUE, the expansion is multiplicative. If FALSE, the expansion is additive.

#### Return Value

Expanded envelope