Don't convert BigFloats to Float64 (#120)

Fix #119.

Author: simonbyrne

src/erf.jl

@@ -24,7 +24,9 @@ for f in (:erf, :erfc, :erfcx, :erfi, :Dawson)
     @eval begin
         ($fname)(z::Complex{Float64}) = Complex{Float64}(ccall(($(string("Faddeeva_",f)),openspecfun), Complex{Float64}, (Complex{Float64}, Float64), z, zero(Float64)))
         ($fname)(z::Complex{Float32}) = Complex{Float32}(ccall(($(string("Faddeeva_",f)),openspecfun), Complex{Float64}, (Complex{Float64}, Float64), Complex{Float64}(z), Float64(eps(Float32))))
-        ($fname)(z::Complex) = ($fname)(Complex{Float64}(z))
+
+        ($fname)(z::Complex) = ($fname)(float(z))
+        ($fname)(z::Complex{<:AbstractFloat}) = throw(MethodError($fname,(z,)))
     end
 end
 
@@ -33,7 +35,9 @@ for f in (:erfcx, :erfi, :Dawson)
     @eval begin
         ($fname)(x::Float64) = ccall(($(string("Faddeeva_",f,"_re")),openspecfun), Float64, (Float64,), x)
         ($fname)(x::Float32) = Float32(ccall(($(string("Faddeeva_",f,"_re")),openspecfun), Float64, (Float64,), Float64(x)))
-        ($fname)(x::Integer) = ($fname)(float(x))
+
+        ($fname)(x::Real) = ($fname)(float(x))
+        ($fname)(x::AbstractFloat) = throw(MethodError($fname,(x,)))
     end
 end
 

test/runtests.jl

@@ -62,6 +62,9 @@ relerrc(z, x) = max(relerr(real(z),real(x)), relerr(imag(z),imag(x)))
     @test SF.erfcx(1.8) ≈ SF.erfcx(big(1.8)) rtol=4*eps()
     @test SF.erfcx(1.8e8) ≈ SF.erfcx(big(1.8e8)) rtol=4*eps()
     @test SF.erfcx(1.8e88) ≈ SF.erfcx(big(1.8e88)) rtol=4*eps()
+
+    @test_throws MethodError erf(big(1.0)*im)
+    @test_throws MethodError erfi(big(1.0))    
 end
 
 @testset "sine and cosine integrals" begin