Linear System
For a function y=f(x), if its derivitive is a constant, then we say it is a linear system.
Example
For function y=2t+1, its derivitive y'=2 y' is a constant Thus y=2t+1 is a linear system. For function y=sin(t), y'=cos(t) y' is not a constant Thus y=sin(t) is a non-linear system.
