From 3b8e0c4112c957410a93432b22b74971bc06f8f8 Mon Sep 17 00:00:00 2001
From: Alexis Placet <alexis.placet@gmail.com>
Date: Wed, 6 May 2026 15:12:17 +0200
Subject: [PATCH] Fix clip function behavior when a_min is greater than a_max
 (#2909)

# Checklist

- [x] The title and commit message(s) are descriptive.
- [x] Small commits made to fix your PR have been squashed to avoid
history pollution.
- [x] Tests have been added for new features or bug fixes.
- [x] API of new functions and classes are documented.

# Description

Address #2860

Now `clips` follow the rule: When a_min is greater than a_max, clip
returns an array in which all values are equal to a_max

---------

Co-authored-by: Alexis Placet <2400067+Alex-PLACET@users.noreply.github.com>
Co-authored-by: Copilot <copilot@github.com>
---
 include/xtensor/core/xmath.hpp | 4 ++--
 test/test_xmath.cpp            | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/xtensor/core/xmath.hpp b/include/xtensor/core/xmath.hpp
index 315e13a82..827e84219 100644
--- a/include/xtensor/core/xmath.hpp
+++ b/include/xtensor/core/xmath.hpp
@@ -606,13 +606,13 @@ namespace xt
             template <class A1, class A2, class A3>
             constexpr auto operator()(const A1& v, const A2& lo, const A3& hi) const
             {
-                return xtl::select(v < lo, lo, xtl::select(hi < v, hi, v));
+                return xtl::select(lo < hi, xtl::select(v < lo, lo, xtl::select(hi < v, hi, v)), hi);
             }
 
             template <class A1, class A2, class A3>
             constexpr auto simd_apply(const A1& v, const A2& lo, const A3& hi) const
             {
-                return xt_simd::select(v < lo, lo, xt_simd::select(hi < v, hi, v));
+                return xt_simd::select(lo < hi, xt_simd::select(v < lo, lo, xt_simd::select(hi < v, hi, v)), hi);
             }
         };
 
diff --git a/test/test_xmath.cpp b/test/test_xmath.cpp
index 8f56e93b9..57771859b 100644
--- a/test/test_xmath.cpp
+++ b/test/test_xmath.cpp
@@ -222,6 +222,15 @@ namespace xt
         EXPECT_EQ(res1, clip(opt_a, 2.0, 4.0));
     }
 
+    TEST(xmath, clip_amin_greater_than_amax)
+    {
+        // NumPy-compatible behavior: when a_min > a_max, all values
+        // are set to a_max (the hi bound).
+        const xarray<int> arr = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+        const xarray<int> expected = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
+        EXPECT_EQ(expected, clip(arr, 8, 1));
+    }
+
     TEST(xmath, sign)
     {
         shape_type shape = {3, 2};