From ba57f6adbe9f5b7635d010b6d8c0c378ff599c42 Mon Sep 17 00:00:00 2001
From: Ralf Ahlbrink <raprism@users.noreply.github.com>
Date: Sun, 26 Apr 2026 15:10:25 +0200
Subject: [PATCH] Fix: Root solver converges prematurely in Std display mode

In Std mode, algebraic::epsilon() used DisplayDigits()+1=21 as
convergence target regardless of Precision. Fixes #1679
---
 src/algebraic.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/algebraic.cc b/src/algebraic.cc
index 649f63a9..eaefd722 100644
--- a/src/algebraic.cc
+++ b/src/algebraic.cc
@@ -1396,7 +1396,9 @@ algebraic_p algebraic::epsilon(int impr)
 {
     int         disp = Settings.DisplayDigits();
     int         prec = Settings.Precision();
-    int         dig  = std::min(disp + 1, std::max(prec - impr, 3));
+    int         dig  = Settings.DisplayMode() == object::ID_Std
+                           ? std::max(prec - impr, 3)
+                           : std::min(disp + 1, std::max(prec - impr, 3));
     algebraic_p eps  = decimal::make(1, -dig);
     return eps;
 }