comment and version number

Author: Miha Zgubic

Project.toml

@@ -1,6 +1,6 @@
 name = "Zygote"
 uuid = "e88e6eb3-aa80-5325-afca-941959d7151f"
-version = "0.6.42"
+version = "0.6.43"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/lib/number.jl

@@ -61,6 +61,8 @@ function ChainRulesCore.rrule(::ZygoteRuleConfig, ::typeof(conj), x::Number)
     return conj(x), conj_pullback
 end
 
+# for real x, ChainRules pulls back a zero real adjoint, whereas we treat x
+# as embedded in the complex numbers and pull back a pure imaginary adjoint
 function ChainRulesCore.rrule(::ZygoteRuleConfig, ::typeof(imag), x::Number)
     imag_pullback(ī) = (NoTangent(), real(ī)*im)
     return imag(x), imag_pullback