hsc3-0.11: Help/UGen/Envelope/envTrapezoid.help.lhs
> :t envTrapezoid
> import Sound.SC3
> let { t = envTrapezoid 0.05 0.95 3 0.1
> ; e = envGen KR 1 1 0 1 RemoveSynth t }
> in audition (out 0 (sinOsc AR 440 0 * e))
> let e = [0,3,-1,-1,0.1,0.5,1,0,0.1,0,1,0,0,1.5,1,0]
> in envTrapezoid 0 0.25 2 0.1 == e