fix abs(::Complex) (#98)

Author: simeonschaub

src/rulesets/Base/base.jl

@@ -52,7 +52,10 @@
 @scalar_rule(adjoint(x), Wirtinger(Zero(), One()))
 @scalar_rule(transpose(x), One())
 
-@scalar_rule(abs(x), sign(x))
+@scalar_rule(abs(x::Real), sign(x))
+@scalar_rule(abs(x::Complex), Wirtinger(x' / 2Ω, x / 2Ω))
+@scalar_rule(hypot(x::Real), sign(x))
+@scalar_rule(hypot(x::Complex), Wirtinger(x' / 2Ω, x / 2Ω))
 @scalar_rule(rem2pi(x, r::RoundingMode), (One(), DNE()))
 
 @scalar_rule(+(x), One())
@@ -81,7 +84,7 @@
 @scalar_rule(sech(x), -tanh(x) * Ω)
 @scalar_rule(csch(x), -coth(x) * Ω)
 
-@scalar_rule(hypot(x, y), (x / Ω, y / Ω))
+@scalar_rule(hypot(x::Real, y::Real), (x / Ω, y / Ω))
 @scalar_rule(sincos(x), @setup((sinx, cosx) = Ω), cosx, -sinx)
 @scalar_rule(atan(y, x), @setup(u = x^2 + y^2), (x / u, -y / u))
 

test/rulesets/Base/base.jl

@@ -104,8 +104,10 @@
             rtol = x isa Complex{Float32} ? 1e-6 : 1e-9
             test_scalar(real, x; rtol=rtol)
             test_scalar(imag, x; rtol=rtol)
-            # TODO: implement correct complex derivative
-            x isa Real && test_scalar(abs, x; rtol=rtol)
+
+            test_scalar(abs, x; rtol=rtol)
+            test_scalar(hypot, x; rtol=rtol)
+
             test_scalar(angle, x; rtol=rtol)
             test_scalar(abs2, x; rtol=rtol)
             test_scalar(conj, x; rtol=rtol)