I'm working with integrals that yield pairs of terms of the form ArcTan[x,y]-ArcTan[x,-y]
or equivalent expressions involving Arg
or complex Log
. For Mathematica's choice of the branch cut, this is equal to 2 ArcTan[x,y]
. However, it appears that the only way to achieve this simplification, or even to get Mathematica to acknowledge that these are equivalent, is to use a custom transformation function like
negt[ArcTan[x_, y_]] := -ArcTan[x, -y]
in Simplify
or FullSimplify
.
Have I missed something?