TITLE: Non-Linear Transformation
QUESTION [6 upvotes]: Can someone explain to me in simple terms what a non-linear transformation is in maths?
I know some single-variable calculus, but I read it has to do with multi-variable calculus, which I'm not familiar with.
If someone could explain it in simple words, that would be helpful.

REPLY [4 votes]: It's a mapping that is not linearly closed. 
either: zero vector is not within the image of the transformation, the transformation is not closed under scalar multiplication, the transformation is not closed under addition.