1. A computer-implemented method of modifying function data, the method comprising: receiving a selection of knots of at least one function, each knot including a function input value, a function output value, and a function tangent value; displaying a transformation region including at least one transformation handle; receiving a position of the at least one transformation handle; and transforming, via one or more processors, the selection of knots in accordance with the position of the at least one transformation handle to determine at least one transformed function, wherein the at least one transformed function includes a non-linear transformation.