Merge pull request #34 from JuliaDiff/domainpow

better fix for domain errors in pow()
JuliaDiff · Jan 10, 2016 · 34ae2b2 · 34ae2b2
2 parents 39eb900 + 175094e
commit 34ae2b2
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diff --git a/src/dual.jl b/src/dual.jl
@@ -231,10 +231,13 @@ abs2dual(z::Dual) = abs2(value(z))
 
 for f in [:^, :(NaNMath.pow)]
     @eval function ($f)(z::Dual, w::Dual)
+        if epsilon(w) == 0.0
+            return $f(z,value(w))
+        end
         val = $f(value(z),value(w))
 
         du =
-        epsilon(z)*value(w)*(($f)(value(z),value(w)-1))+epsilon(w)*($f)(value(z),value(w))*NaNMath.log(value(z))
+        epsilon(z)*value(w)*(($f)(value(z),value(w)-1))+epsilon(w)*($f)(value(z),value(w))*log(value(z))
 
         Dual(val, du)
     end

diff --git a/test/automatic_differentiation_test.jl b/test/automatic_differentiation_test.jl
@@ -134,3 +134,6 @@ test(x, y) = x^2 + y
 
 @test value(mod(Dual(15.23, 1), 10)) == 5.23
 @test epsilon(mod(Dual(15.23, 1), 10)) == 1
+
+@test epsilon(Dual(-2.0,1.0)^2.0) == -4
+@test epsilon(Dual(-2.0,1.0)^Dual(2.0,0.0)) == -4