--LOGARITHMIC SLIDER CONTROL--

These are best for bandpass filter frequency sliders.
Also for volume controls using a 10% or a 20% taper.

BioEra Slider with industry standard log taper,
via ExpressionEvaluator for float & scalar as:
(Math.pow(10,(In2*In1))-1)/(Math.pow(10,In2)-1)*100
(Math.pow(10,(In2*In1))-1)/(Math.pow(10,In2)-1)/10
and reverse aka anti-log aka LH-taper is simply
accomplished by making the X factor negative.

Rotary Control with log taper having input/output range 0-1,
solved using base 10 logarithm, showing the exact X factors:
   Function: V=(10^(X*P)-1)/Y
   0.2*(10^(X)-1) = 10^(X/2)-1
   Lastly substitute Y=10^X-1
Taper:05% X=2.5575071
Taper:10% X=1.9084850
Taper:15% X=1.5066553
Taper:20% X=1.2041199 Y=15
Taper:25% X=0.9542425
Taper:30% X=0.7359535
Taper:35% X=0.5376906
Taper:40% X=0.3521825
Taper:45% X=0.1743003
Taper:50% Impossible Taper

Rotary Control with log taper having input/output range 0-1,
solved using natural logarithm, with an example X factor:
   Function: V=(e^(X*P)-1)/Y
   0.2*(e^(X)-1) = e^(X/2)-1
   Lastly substitute Y=e^X-1
Taper:20% X=2.7725887 Y=15
Taper:50% Impossible Taper

http://www.wolframalpha.com/widgets/gallery/view.jsp?id=bc455327d0772719486c1a3ecf2e96d3