An integrator UGen with exponential decay of past values. This is essentially
the same as Integrator except that instead of supplying the coefficient
directly, it is calculated from a 60 dB decay time. This is the time required
for the integrator to lose 99.9 % of its value or -60dB.
Note: This should not be confused with Lag which does not overshoot due to
integration, but asymptotically follows the input signal.
input signal to be processed