handle signed zero in li6

Expander · Mar 6, 2024 · e27eb5c · e27eb5c
1 parent 3b71df7
commit e27eb5c
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Showing 3 changed files with 19 additions and 5 deletions.
diff --git a/src/li5.rs b/src/li5.rs
@@ -42,7 +42,6 @@ impl Li5<Complex<f64>> for Complex<f64> {
                 let c3 = 0.27415567780803774;
                 let c4 = (25.0/12.0 - (-u).cln())/24.0;
                 let c5 = -1.0/240.0;
-
                 let cs = [
                     -1.1574074074074074e-04, 2.0667989417989418e-07,
                     -1.0935444136502338e-09, 8.6986487449450412e-12,

diff --git a/src/li6.rs b/src/li6.rs
@@ -24,11 +24,11 @@ impl Li6<Complex<f64>> for Complex<f64> {
         let z6  = 1.0173430619844491; // zeta(6)
 
         if self.im == 0.0 && self.re == 0.0 {
-            Complex::new(0.0, 0.0)
+            *self
         } else if self.im == 0.0 && self.re == 1.0 {
-            Complex::new(z6, 0.0)
+            Complex::new(z6, self.im)
         } else if self.im == 0.0 && self.re == -1.0 {
-            Complex::new(-31.0/32.0*z6, 0.0)
+            Complex::new(-31.0/32.0*z6, self.im)
         } else {
             let nz  = self.norm();
             let pz  = self.arg();
@@ -43,7 +43,6 @@ impl Li6<Complex<f64>> for Complex<f64> {
                 let c4 = 0.068538919452009435;
                 let c5 = (137.0/60.0 - (-u).cln())/120.0;
                 let c6 = -1.0/1440.0;
-
                 let cs = [
                     -1.6534391534391534e-05, 2.2964432686654909e-08,
                     -9.9413128513657614e-11, 6.6912682653423394e-13,

diff --git a/tests/li6.rs b/tests/li6.rs
@@ -35,3 +35,19 @@ fn test_values() {
         assert_eq_complex!(v.li6(), li6, eps);
     }
 }
+
+
+#[test]
+fn test_signed_zero() {
+    let pz64 = 0.0_f64;
+    let nz64 = -0.0_f64;
+
+    assert!(Complex::new(pz64, pz64).li6().re.is_sign_positive());
+    assert!(Complex::new(pz64, pz64).li6().im.is_sign_positive());
+    assert!(Complex::new(pz64, nz64).li6().re.is_sign_positive());
+    assert!(Complex::new(pz64, nz64).li6().im.is_sign_negative());
+    assert!(Complex::new(nz64, pz64).li6().re.is_sign_negative());
+    assert!(Complex::new(nz64, pz64).li6().im.is_sign_positive());
+    assert!(Complex::new(nz64, nz64).li6().re.is_sign_negative());
+    assert!(Complex::new(nz64, nz64).li6().im.is_sign_negative());
+}