From 6754f5783adb2bc2ff468fc18f6c5e5dc1028478 Mon Sep 17 00:00:00 2001
From: "Ryan M. Richard" <rrichard@ameslab.gov>
Date: Tue, 1 Sep 2026 11:04:16 -0500
Subject: [PATCH] account for uncertainty in log

---
 .../generate/generate_eigenvalues.cpp           | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tests/cxx/unit_tests/tensorwrapper/generate/generate_eigenvalues.cpp b/tests/cxx/unit_tests/tensorwrapper/generate/generate_eigenvalues.cpp
index ebac9fdb..85ed270a 100644
--- a/tests/cxx/unit_tests/tensorwrapper/generate/generate_eigenvalues.cpp
+++ b/tests/cxx/unit_tests/tensorwrapper/generate/generate_eigenvalues.cpp
@@ -25,6 +25,21 @@ using namespace tensorwrapper::generate;
 using namespace tensorwrapper::operations;
 using namespace tensorwrapper::utilities;
 
+namespace {
+// Composing two transcendental functions (log then exp) forces a rigorous
+// Interval to widen by more than the default 1e-16 tolerance even when
+// compared against itself, since an interval's difference with itself is not
+// zero-width unless the interval is a single point. This tolerance accounts
+// for that unavoidable widening.
+template<typename T>
+constexpr double log_spacing_tol =
+  std::is_same_v<T, float> || std::is_same_v<T, types::ufloat> ||
+      std::is_same_v<T, types::ifloat> || std::is_same_v<T, types::afloat> ||
+      std::is_same_v<T, types::tafloat> || std::is_same_v<T, types::tmfloat> ?
+    5e-3 :
+    1e-9;
+} // namespace
+
 TEMPLATE_LIST_TEST_CASE("generate_eigenvalues", "",
                         types::floating_point_types) {
     SECTION("n == 1") {
@@ -70,7 +85,7 @@ TEMPLATE_LIST_TEST_CASE("generate_eigenvalues", "",
         auto gen    = make_rng(1);
         auto result = generate_eigenvalues<TestType>(spec, gen);
         auto corr   = make_tensor({3}, expected);
-        REQUIRE(approximately_equal(result, corr));
+        REQUIRE(approximately_equal(result, corr, log_spacing_tol<TestType>));
     }
 
     SECTION("degenerate spacing") {