extend tests for eta function

Expander · Oct 5, 2023 · f02f039 · f02f039
1 parent c705fce
commit f02f039
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Showing 2 changed files with 34 additions and 19 deletions.
diff --git a/src/Eta.jl b/src/Eta.jl
@@ -61,7 +61,7 @@ const MINUS_ETA_NEG = (
 )
 
 # returns Li(n,-1) = (2^(1 - n) - 1)*zeta(n)
-function neg_eta(n::Integer, T=Float64)
+function neg_eta(n::Integer, T)
     if T == Float64
         neg_eta_f46(n)
     else
@@ -90,7 +90,15 @@ function neg_eta_f46(n::Integer)::Float64
 end
 
 function neg_eta_big(n::Integer)::BigFloat
-    if n == 1
+    if n < 0
+        if iseven(n)
+            BigFloat("0")
+        else
+            (exp2(1 - n) - one(BigFloat))*zeta_big(n)
+        end
+    elseif n == 0
+        BigFloat("-0.5")
+    elseif n == 1
         -log(big(2))
     else
         (exp2(1 - n) - one(BigFloat))*zeta_big(n)

diff --git a/test/Eta.jl b/test/Eta.jl
@@ -1,19 +1,26 @@
 @testset "eta" begin
-    @test PolyLog.neg_eta(-222) ==  0.0
-    @test PolyLog.neg_eta(-221) == -Inf
-    @test PolyLog.neg_eta(-220) ==  0.0
-    @test PolyLog.neg_eta(-219) == Inf
-    @test PolyLog.neg_eta(-218) ==  0.0
-    @test PolyLog.neg_eta(-217) == -1.8184610414701105e306
-    @test PolyLog.neg_eta(  -4) ==  0.0
-    @test PolyLog.neg_eta(  -3) ==  1/8
-    @test PolyLog.neg_eta(  -2) ==  0.0
-    @test PolyLog.neg_eta(  -1) == -0.25
-    @test PolyLog.neg_eta(   1) == -0.69314718055994531
-    @test PolyLog.neg_eta(   2) == -0.82246703342411322
-    @test PolyLog.neg_eta(  52) == -0.9999999999999998
-    @test PolyLog.neg_eta(  53) == -0.9999999999999999
-    @test PolyLog.neg_eta(  54) == -0.9999999999999999
-    @test PolyLog.neg_eta(  55) == -1.0
-    @test PolyLog.neg_eta(  56) == -1.0
+    @test PolyLog.neg_eta(-222, Float64) ==  0.0
+    @test PolyLog.neg_eta(-221, Float64) == -Inf
+    @test PolyLog.neg_eta(-220, Float64) ==  0.0
+    @test PolyLog.neg_eta(-219, Float64) == Inf
+    @test PolyLog.neg_eta(-218, Float64) ==  0.0
+    @test PolyLog.neg_eta(-217, Float64) == -1.8184610414701105e306
+    @test PolyLog.neg_eta(  -4, Float64) ==  0.0
+    @test PolyLog.neg_eta(  -3, Float64) ==  1/8
+    @test PolyLog.neg_eta(  -2, Float64) ==  0.0
+    @test PolyLog.neg_eta(  -1, Float64) == -0.25
+    @test PolyLog.neg_eta(   0, Float64) == -0.5
+    @test PolyLog.neg_eta(   1, Float64) == -0.69314718055994531
+    @test PolyLog.neg_eta(   2, Float64) == -0.82246703342411322
+    @test PolyLog.neg_eta(  52, Float64) == -0.9999999999999998
+    @test PolyLog.neg_eta(  53, Float64) == -0.9999999999999999
+    @test PolyLog.neg_eta(  54, Float64) == -0.9999999999999999
+    @test PolyLog.neg_eta(  55, Float64) == -1.0
+    @test PolyLog.neg_eta(  56, Float64) == -1.0
+
+    @test PolyLog.neg_eta(-2, BigFloat) == BigFloat("0")
+    @test PolyLog.neg_eta(-1, BigFloat) == (big(2)^2 - one(BigFloat))*PolyLog.zeta(-1, BigFloat)
+    @test PolyLog.neg_eta( 0, BigFloat) == BigFloat("-0.5")
+    @test PolyLog.neg_eta( 1, BigFloat) == -log(big(2))
+    @test PolyLog.neg_eta( 2, BigFloat) == (inv(big(2)) - one(BigFloat))*PolyLog.zeta(2, BigFloat)
 end