I'm trying to simplify an expression with sums of
ArcTan, for which I've written a transformation rule that works for simple sums, so that
ArcTan[a] + ArcTan[b] -> ArcTan[(a+b)/(1-ab)]. However, it fails for terms of the type
5 ArcTan[a] + ArcTan[b]. One way to simplify this expression would be to expand the integer into a sum of units, then transform repeatedly until the expression consists of only one
ArcTan, but I haven't been able so far to find the way.
Plusto no avail.