message: Corrected typo in formula
  It looks like there is a minus sign missing in there, see https://www.wolframalpha.com/input/?i=(((1%2Bsqrt(x))+%2F+(1+-+sqrt(x)))+-+1.5)+%2F+(((1%2Bsqrt(x))+%2F+(1+-+sqrt(x)))+%2B+1.5)
  I'm not sure what the code does though
diff: @@ -915,7 +915,7 @@ $$
  Since the clear coat layer's IOR is fixed, we can combine both steps to simplify:
  $$
  -f_{0_{base}} = \frac{\left( 1 - 5 \sqrt{\fNormal} \right) ^2}{\left( 5 \sqrt{\fNormal} \right) ^2}
  +f_{0_{base}} = \frac{\left( 1 - 5 \sqrt{\fNormal} \right) ^2}{\left( 5 - \sqrt{\fNormal} \right) ^2}
  $$
  We should also modify the base layer's apparent roughness based on the IOR of the clear coat layer but this is something we have opted to leave out for now.
  