Nice find! In general, you can send errata/bugs to authors@pbrt.org, but we got this one. :-) It looks like an equation that MathJax wasn't happy with. I've g

Nice find! In general, you can send errata/bugs to authors@pbrt.org, but we got this one. :-) It looks like an equation that MathJax wasn't happy with. I've got it fixed now and will include that fix in a push to the site in a little bit. If you want to be listed as something other than "OnACoffeeBreak" in the errata credits, send me an email (matt@pharr.org). Thanks again!