transeg — Constructs a user-definable envelope.
ares transeg ia, idur, itype, ib [, idur2] [, itype] [, ic] ...
kres transeg ia, idur, itype, ib [, idur2] [, itype] [, ic] ...
ia -- starting value.
ib, ic, etc. -- value after idur seconds.
idur, idur2, etc. -- duration in seconds of segment
itype, itype2, etc. -- if 0, a straight line is produced. If non-zero, then transeg creates the following curve, for n steps:
ibeg + (ivalue - ibeg) * (1 - exp( i*itype/(n-1) )) / (1 - exp(itype))
If itype > 0, there is a slowly rising, fast decaying (convex) curve, while if itype < 0, the curve is fast rising, slowly decaying (concave). See also GEN16.