Interpolation CHOP

In the Interpolate CHOP, linear interpolation equals math average:

For lerp(factor, a, b) = factor*a + (1.0 - factor)*b, it means here that
factor equals a particular function:
(a - b)/2(a - 2)

So either it outputs the first curve, either the second, either it does a math average of the two ?

Will it not be interesting to have a factor parameter to play with ?

Also, how is it that other interpolation modes seem to have no effect on the curve, and how to use them ?
Interpolation_Questions.tox (2.01 KB)