/sci/ - Science & Math

I think there's a mistake here, on the statement about the integrals along the circular arc.
If we had [math]j'(\tau) = j'(-\tau^{-1})[/math], then that would be true, but [math]j(\tau) = j(-\tau^{-1})[/math] implies [math]j'(\tau) = \tau^{-2} j'(-\tau^{-1})[/math]. Am I right?