unnecessary branch

Author: cossio

src/rules.jl

@@ -83,11 +83,7 @@ _abs_deriv(x) = signbit(x) ? -one(x) : one(x)
 @define_diffrule Base.:\(x, y) = :( -($y / $x / $x)    ), :( one($y) / ($x)     )
 @define_diffrule Base.:^(x, y) = :( $y * ($x^($y - 1)) ), :( ($x isa Real && $x<=0) ? Base.oftype(float($x), NaN) : ($x^$y)*log($x) )
 
-if VERSION < v"0.7-"
-    @define_diffrule Base.atan2(x, y)   = :( $y / ($x^2 + $y^2)                                 ), :( -$x / ($x^2 + $y^2)                                                     )
-else
-    @define_diffrule Base.atan(x, y)    = :( $y / ($x^2 + $y^2)                                 ), :( -$x / ($x^2 + $y^2)                                                     )
-end
+@define_diffrule Base.atan(x, y)    = :( $y / ($x^2 + $y^2)                                 ), :( -$x / ($x^2 + $y^2)                                                     )
 @define_diffrule Base.hypot(x, y)  = :( $x / hypot($x, $y)                                      ), :(  $y / hypot($x, $y)                                                     )
 @define_diffrule Base.log(b, x)    = :( log($x) * inv(-log($b)^2 * $b)                          ), :( inv($x) / log($b)                                                       )