From e567151ce3fcb0c596a80e57f4255c49c4fedea5 Mon Sep 17 00:00:00 2001
From: Rasmus Munk Larsen <rmlarsen@gmail.com>
Date: Wed, 25 Feb 2026 19:03:01 -0800
Subject: [PATCH] Fix ambiguous static_cast in JacobiSVD blocking threshold
 computation

The L2 cache size threshold computation used numext::sqrt with a
static_cast<RealScalar>, which fails to compile when RealScalar is
AnnoyingScalar (a test-only type with multiple conversion constructors).
Since this is a pure cache-size computation unrelated to the matrix
scalar type, use std::sqrt(double) instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 Eigen/src/SVD/JacobiSVD.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Eigen/src/SVD/JacobiSVD.h b/Eigen/src/SVD/JacobiSVD.h
index e9c0f0df2..77ef3bed8 100644
--- a/Eigen/src/SVD/JacobiSVD.h
+++ b/Eigen/src/SVD/JacobiSVD.h
@@ -774,7 +774,7 @@ JacobiSVD<MatrixType, Options>& JacobiSVD<MatrixType, Options>::compute_impl(con
       const Index blockingThreshold = EIGEN_JACOBI_SVD_BLOCKING_THRESHOLD;
 #else
       const Index blockingThreshold =
-          static_cast<Index>(numext::sqrt(static_cast<RealScalar>(l2CacheSize() / sizeof(float))));
+          static_cast<Index>(std::sqrt(static_cast<double>(l2CacheSize() / sizeof(float))));
 #endif
 
       if (n >= blockingThreshold) {