freq = 2; // wiggles per second
amp = 100;
minWiggle = -80
maxWiggle = -20;
w = wiggle(freq,amp)[2] - value[2];
value + [0, 0, linear(w, -amp, +amp, minWiggle, maxWiggle)]
hi = -20;
lo = -80;
freq = 2;
amp = Math.abs(hi - lo)/2;
offset = (hi + lo)/2;
wiggle(freq,amp) + offset
Dan