johnmyleswhite/Calculus.jl — pull request #13 by ivarne (2013-06-29 06:23:21+00:00)
Title: Error in The Quotient Rule

Differentiation of a fraction is wrong if the numerator or denominator independent of the variable differentiated with respect to.
It looks like somebody forgot to divide by (denominator)^2 for the special cases where one of the derivatives is 0