special functions for missing (#103)

* special functions for missing
* add build log to .gitignore

Author: fredrikekre

.gitignore

@@ -2,6 +2,7 @@
 *.jl.*.cov
 *.jl.mem
 deps/deps.jl
+deps/build.log
 deps/downloads
 deps/usr
 deps/src

src/SpecialFunctions.jl

@@ -76,4 +76,17 @@ include("sincosint.jl")
 include("gamma.jl")
 include("deprecated.jl")
 
+@static if isdefined(Base, :missing)
+    for f in (:digamma, :erf, :erfc, :erfcinv, :erfcx, :erfi, :erfinv,
+              :eta, :gamma, :invdigamma, :lfactorial, :lgamma, :trigamma)
+        @eval $(f)(::Missing) = missing
+    end
+    for f in (:beta, :lbeta)
+        @eval $(f)(::Number, ::Missing) = missing
+        @eval $(f)(::Missing, ::Number) = missing
+        @eval $(f)(::Missing, ::Missing) = missing
+    end
+    polygamma(m::Integer, x::Missing) = missing
+end
+
 end # module

test/runtests.jl

@@ -641,3 +641,18 @@ end
 
     @test beta(big(1.0),big(1.2)) ≈ beta(1.0,1.2) rtol=4*eps()
 end
+
+@static if isdefined(Base, :missing)
+    @testset "missing data" begin
+        for f in (digamma, erf, erfc, erfcinv, erfcx, erfi, erfinv, eta, gamma,
+                  invdigamma, lfactorial, lgamma, trigamma)
+            @test f(missing) === missing
+        end
+        for f in (beta, lbeta)
+            @test f(1.0, missing) === missing
+            @test f(missing, 1.0) === missing
+            @test f(missing, missing) === missing
+        end
+        @test polygamma(4, missing) === missing
+    end
+end