ActiveAt finds the modes active segment at time t.

Cut cuts the given mode around the time t.

MagnitudeAt returns the magnitude of the mode at t.

MaxSegmentAfter returns the index in mode.Segments of the segment with the largest magnitude after the given time.

MinAt returns the mode with the smalled magnitude at the given time, and that magnitude.

Shift adjusts the given mode until it's start time is offset by d.

Sum combines all the given modes together into a single mode.