Boltzmann-func
The formula for the Boltzmann Function, Boltzmann(x, A1, A2, x0, dx) function is:
y = A2 + (A1-A2)/(1 + exp((x-x0)/dx))
where:
A1 is the initial value.
A2 is the final value.
x0 is the center.
dx is a time constant.