Refactor

kimwalisch · Mar 18, 2024 · 2fa7306 · 2fa7306
1 parent 3cbee9a
commit 2fa7306
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/src/RiemannR.cpp b/src/RiemannR.cpp
@@ -299,7 +299,14 @@ T RiemannR_inverse(T x)
   // the precision of the libc math functions is very limited.
   for (int i = 0; i < 100; i++)
   {
-    T term = (RiemannR(t) - x) / RiemannR_prime(t);
+    T term;
+
+    if (x < 1e10)
+      // Converges faster for small x
+      term = (RiemannR(t) - x) / RiemannR_prime(t);
+    else
+      // Converges faster for large x
+      term = (RiemannR(t) - x) / std::log(t);
 
     // Not converging anymore
     if (std::abs(term) >= std::abs(old_term))