Fix up my garbage and add a test

JuliaStats · Jul 16, 2017 · 5df2557 · 5df2557
1 parent e724056
commit 5df2557
Show file tree

Hide file tree

Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/src/univariate/discrete/poissonbinomial.jl b/src/univariate/discrete/poissonbinomial.jl
@@ -149,8 +149,8 @@ end
 if VERSION >= v"0.7.0-DEV.602"
     function _dft(x::Vector{T}) where T
         n = length(x)
-        y = fill!(copy(x), zero(complex(float(T))))
-        @inbounds for j = 0:n-1, i = 0:n-1
+        y = Vector{complex(float(T))}(n)
+        @inbounds for j = 0:n-1, k = 0:n-1
             y[k+1] += x[j+1] * cis(-2π * j * k / n)
         end
         return y

diff --git a/test/poissonbinomial.jl b/test/poissonbinomial.jl
@@ -74,3 +74,18 @@ for (n₁, n₂, n₃, p₁, p₂, p₃) in [(10, 10, 10, 0.1, 0.5, 0.9),
         @test isapprox(pdf(d, k), m, atol=1e-15)
     end
 end
+
+# Test the _dft helper function
+@testset "_dft" begin
+    x = Distributions._dft(collect(1:8))
+    # Comparator computed from FFTW
+    fftw_fft = [36.0 + 0.0im,
+                -4.0 + 9.65685424949238im,
+                -4.0 + 4.0im,
+                -4.0 + 1.6568542494923806im,
+                -4.0 + 0.0im,
+                -4.0 - 1.6568542494923806im,
+                -4.0 - 4.0im,
+                -4.0 - 9.65685424949238im]
+    @test x ≈ fftw_fft
+end