Pseg defines a function of time as a breakpoint envelope using the same parameters as Env. These patterns can be used to describe tempo or dynamic variations independent of the rhythmic patterns that express them.
Pseg.new(levels, durs: 1, curves: 'lin', repeats: 1)
Arguments:
levels 
A Pattern that returns the levels. The first level is the initial value of the envelope, all subsequent values are interpolated. 
durs 
A Pattern that returns segments durations in beats. 
curves 
a Symbol, Float, or an Array of those. Determines the shape of the segments. 
repeats 
a number.
The possible values are:
\step   flat segments.  \linear  \lin  linear segments, the default.  \exponential  \exp  natural exponential growth and decay. In this case, the levels must all be nonzero and the have the same sign.  \sine  \sin  sinusoidal S shaped segments.  \welch  \wel  sinusoidal segments shaped like the sides of a Welch window.  \squared  \sqr  squared segment.  \cubed  \cub  cubed segment.  a Float   a curvature value for all segments. 0 means linear, positive and negative numbers curve the segment up and down.  an Array of symbols or floats   curvature values for each segment. 
