Fix inconsistency of pdf/cdf of Uniform (#1682)

* Fix inconsistency of `pdf`/`cdf` of `Uniform` * Fix existing tests * Fixes * Fix
JuliaStats · Feb 23, 2023 · 610bc12 · 610bc12
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commit 610bc12
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Showing 3 changed files with 41 additions and 27 deletions.
diff --git a/src/univariate/continuous/uniform.jl b/src/univariate/continuous/uniform.jl
@@ -72,12 +72,16 @@ entropy(d::Uniform) = log(d.b - d.a)
 #### Evaluation
 
 function pdf(d::Uniform, x::Real)
-    val = inv(d.b - d.a)
+    # include dependency on `x` for return type to be consistent with `cdf`
+    a, b, _ = promote(d.a, d.b, x)
+    val = inv(b - a)
     return insupport(d, x) ? val : zero(val)
 end
 function logpdf(d::Uniform, x::Real)
-    diff = d.b - d.a
-    return insupport(d, x) ? -log(diff) : log(zero(diff))
+    # include dependency on `x` for return type to be consistent with `logcdf`
+    a, b, _ = promote(d.a, d.b, x)
+    val = - log(b - a)
+    return insupport(d, x) ? val : oftype(val, -Inf)
 end
 gradlogpdf(d::Uniform, x::Real) = zero(partype(d)) / oneunit(x)
 

diff --git a/test/univariate/continuous/uniform.jl b/test/univariate/continuous/uniform.jl
@@ -1,6 +1,7 @@
 using Distributions
 using ChainRulesTestUtils
 using OffsetArrays
+using StatsFuns
 
 using Random
 using Test
@@ -80,4 +81,37 @@ using Test
             end
         end
     end
+    # issue #1677
+    @testset "consistency of pdf and cdf" begin
+        for T in (Int, Float32, Float64)
+            d = Uniform{T}(T(2), T(4))
+            for S in (Int, Float32, Float64)
+                TS = float(promote_type(T, S))
+
+                @test @inferred(pdf(d, S(1))) === TS(0)
+                @test @inferred(pdf(d, S(3))) === TS(1//2)
+                @test @inferred(pdf(d, S(5))) === TS(0)
+
+                @test @inferred(logpdf(d, S(1))) === TS(-Inf)
+                @test @inferred(logpdf(d, S(3))) === -TS(logtwo)
+                @test @inferred(logpdf(d, S(5))) === TS(-Inf)
+
+                @test @inferred(cdf(d, S(1))) === TS(0)
+                @test @inferred(cdf(d, S(3))) === TS(1//2)
+                @test @inferred(cdf(d, S(5))) === TS(1)
+
+                @test @inferred(logcdf(d, S(1))) === TS(-Inf)
+                @test @inferred(logcdf(d, S(3))) === -TS(logtwo)
+                @test @inferred(logcdf(d, S(5))) === TS(0)
+
+                @test @inferred(ccdf(d, S(1))) === TS(1)
+                @test @inferred(ccdf(d, S(3))) === TS(1//2)
+                @test @inferred(ccdf(d, S(5))) === TS(0)
+
+                @test @inferred(logccdf(d, S(1))) === TS(0)
+                @test @inferred(logccdf(d, S(3))) === -TS(logtwo)
+                @test @inferred(logccdf(d, S(5))) === TS(-Inf)
+            end
+        end
+    end
 end
diff --git a/test/univariates.jl b/test/univariates.jl
@@ -177,30 +177,6 @@ end
     @test invlogccdf(d, log(0.6)) isa Int
 end
 
-@testset "Uniform type inference" begin
-    for T in (Int, Float32)
-        d = Uniform{T}(T(2), T(3))
-        FT = float(T)
-        XFT = promote_type(FT, Float64)
-
-        @test @inferred(pdf(d, 1.5)) === zero(FT)
-        @test @inferred(pdf(d, 2.5)) === one(FT)
-        @test @inferred(pdf(d, 3.5)) === zero(FT)
-
-        @test @inferred(logpdf(d, 1.5)) === FT(-Inf)
-        @test @inferred(logpdf(d, 2.5)) === -zero(FT) # negative zero
-        @test @inferred(logpdf(d, 3.5)) === FT(-Inf)
-
-        @test @inferred(cdf(d, 1.5)) === zero(XFT)
-        @test @inferred(cdf(d, 2.5)) === XFT(1//2)
-        @test @inferred(cdf(d, 3.5)) === one(XFT)
-
-        @test @inferred(ccdf(d, 1.5)) === one(XFT)
-        @test @inferred(ccdf(d, 2.5)) === XFT(1//2)
-        @test @inferred(ccdf(d, 3.5)) === zero(XFT)
-    end
-end
-
 # #1471
 @testset "InverseGamma constructor (#1471)" begin
     @test_throws DomainError InverseGamma(-1, 2)