Merge pull request #497 from RainerHeintzmann/master

Add rule for `sincospi`

Author: mcabbott

Project.toml

@@ -1,6 +1,6 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "1.5.1"
+version = "1.6.0"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/rulesets/Base/fastmath_able.jl

@@ -48,6 +48,10 @@ let
         # Trig-Multivariate
         @scalar_rule atan(y, x) @setup(u = x ^ 2 + y ^ 2) (x / u, -y / u)
         @scalar_rule sincos(x) @setup((sinx, cosx) = Ω) cosx -sinx
+        # the position of the minus sign below warrants the correct type for π  
+        if VERSION ≥ v"1.6"
+            @scalar_rule sincospi(x) @setup((sinpix, cospix) = Ω) (π * cospix)  (π * (-sinpix))
+        end
 
         # exponents
         @scalar_rule cbrt(x) inv(3 * Ω ^ 2)

test/rulesets/Base/fastmath_able.jl

@@ -64,6 +64,14 @@ const FASTABLE_AST = quote
                 test_frule(sincos, randn(T))
                 test_rrule(sincos, randn(T); output_tangent=Δz)
             end
+            if VERSION ≥ v"1.6"
+                @testset "sincospi(x::$T)" for T in (Float64, ComplexF64)
+                    Δz = Tangent{Tuple{T,T}}(randn(T), randn(T))
+
+                    test_frule(sincospi, randn(T))
+                    test_rrule(sincospi, randn(T); output_tangent=Δz)
+                end
+            end
         end
     end