From 4454d8f233e813c3eb10d6ad1ffb823c112c9752 Mon Sep 17 00:00:00 2001
From: Alexander Voigt <ahgvoigt@gmail.com>
Date: Thu, 5 Oct 2023 14:54:48 +0200
Subject: [PATCH] stable return type

---
 src/Factorial.jl  | 12 ++++++------
 test/Factorial.jl | 10 ++++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/Factorial.jl b/src/Factorial.jl
index 883d0cd..68851f7 100644
--- a/src/Factorial.jl
+++ b/src/Factorial.jl
@@ -124,11 +124,11 @@ const INVERSE_FACTORIALS = (
 function fac(n::Integer, T)
     if n < 0
         throw(DomainError(n, "fac not implemented for n < 0"))
-    elseif T == Float64
+    elseif issimplefloat(T)
         if n + 1 <= length(FACTORIALS)
-            FACTORIALS[n + 1]
+            convert(T, FACTORIALS[n + 1])
         else
-            Inf
+            convert(T, Inf)
         end
     else
         BigFloat(factorial(big(n)))
@@ -139,11 +139,11 @@ end
 function inv_fac(n::Integer, T)
     if n < 0
         throw(DomainError(n, "inv_fac not implemented for n < 0"))
-    elseif T == Float64
+    elseif issimplefloat(T)
         if n + 1 <= length(INVERSE_FACTORIALS)
-            INVERSE_FACTORIALS[n + 1]
+            convert(T, INVERSE_FACTORIALS[n + 1])
         else
-            0.0
+            zero(T)
         end
     else
         BigFloat(inv(factorial(big(n))))
diff --git a/test/Factorial.jl b/test/Factorial.jl
index 4217612..5235d03 100644
--- a/test/Factorial.jl
+++ b/test/Factorial.jl
@@ -2,6 +2,11 @@
     @test_throws DomainError PolyLog.fac(-1, Float64)
     @test_throws DomainError PolyLog.fac(-1, BigFloat)
 
+    @test typeof(PolyLog.fac(1, Float16)) == Float16
+    @test typeof(PolyLog.fac(1, Float32)) == Float32
+    @test typeof(PolyLog.fac(1, Float64)) == Float64
+    @test typeof(PolyLog.fac(1, BigFloat)) == BigFloat
+
     @test PolyLog.fac(  0, Float64) == 1.0
     @test PolyLog.fac(  1, Float64) == 1.0
     @test PolyLog.fac(  2, Float64) == 2.0
@@ -22,6 +27,11 @@ end
     @test_throws DomainError PolyLog.inv_fac(-1, Float64)
     @test_throws DomainError PolyLog.inv_fac(-1, BigFloat)
 
+    @test typeof(PolyLog.inv_fac(1, Float16)) == Float16
+    @test typeof(PolyLog.inv_fac(1, Float32)) == Float32
+    @test typeof(PolyLog.inv_fac(1, Float64)) == Float64
+    @test typeof(PolyLog.inv_fac(1, BigFloat)) == BigFloat
+
     @test PolyLog.inv_fac(  0, Float64) == 1.0
     @test PolyLog.inv_fac(  1, Float64) == 1.0
     @test PolyLog.inv_fac(  2, Float64) == 1/2