From 81c979326660865f29cdaf58241af71e8439a9f1 Mon Sep 17 00:00:00 2001
From: Axel Huebl <axel.huebl@plasma.ninja>
Date: Fri, 3 Jan 2025 23:42:12 -0800
Subject: [PATCH] Add Algorithm: `almost_equal` (`almostEqual`) (#398)

Add floating point _almost equal_ comparison from `AMReX_Algorithm`.
---
 src/Base/Algorithm.cpp  | 31 +++++++++++++++++++++++++++++++
 src/Base/CMakeLists.txt |  1 +
 src/pyAMReX.cpp         |  2 ++
 3 files changed, 34 insertions(+)
 create mode 100644 src/Base/Algorithm.cpp

diff --git a/src/Base/Algorithm.cpp b/src/Base/Algorithm.cpp
new file mode 100644
index 00000000..5c468302
--- /dev/null
+++ b/src/Base/Algorithm.cpp
@@ -0,0 +1,31 @@
+/* Copyright 2021-2025 The AMReX Community
+ *
+ * Authors: Axel Huebl
+ * License: BSD-3-Clause-LBNL
+ */
+#include "pyAMReX.H"
+
+#include <AMReX_Algorithm.H>
+
+#include <type_traits>
+
+
+void init_Algorithm (py::module& m)
+{
+    using namespace amrex;
+
+    m.def(
+        "almost_equal",
+        &almostEqual<Real>,
+        py::arg("x"), py::arg("y"), py::arg("ulp")=2
+    );
+
+    if constexpr (!std::is_same_v<Real, ParticleReal>)
+    {
+        m.def(
+            "almost_equal",
+            &almostEqual<ParticleReal>,
+            py::arg("x"), py::arg("y"), py::arg("ulp")=2
+        );
+    }
+}
diff --git a/src/Base/CMakeLists.txt b/src/Base/CMakeLists.txt
index b80c820b..0db7d7cb 100644
--- a/src/Base/CMakeLists.txt
+++ b/src/Base/CMakeLists.txt
@@ -1,6 +1,7 @@
 foreach(D IN LISTS AMReX_SPACEDIM)
     target_sources(pyAMReX_${D}d
       PRIVATE
+        Algorithm.cpp
         AMReX.cpp
         Arena.cpp
         Array4.cpp
diff --git a/src/pyAMReX.cpp b/src/pyAMReX.cpp
index aebe7403..ed52c2be 100644
--- a/src/pyAMReX.cpp
+++ b/src/pyAMReX.cpp
@@ -12,6 +12,7 @@
 
 
 // forward declarations of exposed classes
+void init_Algorithm(py::module&);
 void init_AMReX(py::module&);
 void init_Arena(py::module&);
 void init_Array4(py::module&);
@@ -90,6 +91,7 @@ PYBIND11_MODULE(amrex_3d_pybind, m) {
     init_AMReX(m);
     init_Arena(m);
     init_Dim3(m);
+    init_Algorithm(m);
     init_IntVect(m);
     init_IndexType(m);
     init_RealVect(m);