Fix for #47 (#50)

* fix for #47

* added tests

* added promote to pow

Author: torfjelde

src/NaNMath.jl

@@ -22,7 +22,9 @@ sqrt(x::Real) = x < 0.0 ? NaN : Base.sqrt(x)
 # Don't override built-in ^ operator
 pow(x::Float64, y::Float64) = ccall((:pow,libm),  Float64, (Float64,Float64), x, y)
 pow(x::Float32, y::Float32) = ccall((:powf,libm), Float32, (Float32,Float32), x, y)
-pow(x::Number,y::Number) = pow(float(x),float(y))
+# Need `promote` here, otherwise we'll end up with an infinite recursion
+# in the case of `x` and `y` being different floating types.
+pow(x::Number, y::Number) = pow(promote(float(x), float(y))...)
 
 """
 NaNMath.sum(A)

test/runtests.jl

@@ -4,6 +4,13 @@ using Test
 @test isnan(NaNMath.log(-10))
 @test isnan(NaNMath.log1p(-100))
 @test isnan(NaNMath.pow(-1.5,2.3))
+@test isnan(NaNMath.pow(-1.5f0,2.3f0))
+@test isnan(NaNMath.pow(-1.5,2.3f0))
+@test isnan(NaNMath.pow(-1.5f0,2.3))
+@test NaNMath.pow(-1.5f0,2.3f0) isa Float32
+@test NaNMath.pow(-1.5f0,2.3) isa Float64
+@test NaNMath.pow(-1.5,2.3f0) isa Float64
+@test NaNMath.pow(-1.5,2.3) isa Float64
 @test isnan(NaNMath.sqrt(-5))
 @test NaNMath.sqrt(5) == Base.sqrt(5)
 @test NaNMath.sum([1., 2., NaN]) == 3.0