Slider with square law output wrt position:

Calculate V=(P+X*P^2)/Y and substitute Y=X+1

Selections & Formula for X in forward taper:
64.0, 32.0, 16.0, 8.0, 4.0, 2.0, 1.0, 0.5, 0.25
(In1+In2*In1*In1)/(In2+1)*100

Selections & Formula for X in reverse taper:
-0.25, -0.5, -1.0, -2.0, -4.0, -8.0, -16.0, -32.0, -64.0
(1-((1-In1)-In2*(1-In1)*(1-In1))/(1-In2))*100