class:: InterplXYC
summary:: envelope specification
related:: Classes/InterplEnv
categories:: Control, Envelopes

description::
Takes sets of x, y and curve values and returns a new instance of InterplEnv.
x values can be negative (for use in indexing with negative values or signals).
See link::Classes/InterplEnv:: Help for more info.

Examples::

code::
a = InterplXYC([0, 0, \lin], [1, 2, \sin], [2, 0]);
a.plot;

a = InterplXYC([[-1, 1, \sin], [0, 2, \lin], [1, 0]]);
a.plot;
a.at(-0.5);
a.at(0.2);
::
