From 7c54178aee6fd6dcca200da1eb98e49d0ea07187 Mon Sep 17 00:00:00 2001
From: John Haiducek <jhaiduce@gmail.com>
Date: Mon, 22 Jan 2024 14:11:43 -0500
Subject: [PATCH] Fixed bug where normalise_angle would stall when passed very
 large numbers.

---
 src/eckit/geometry/CoordinateHelpers.cc | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/eckit/geometry/CoordinateHelpers.cc b/src/eckit/geometry/CoordinateHelpers.cc
index 48ab93117..d8635d4ca 100644
--- a/src/eckit/geometry/CoordinateHelpers.cc
+++ b/src/eckit/geometry/CoordinateHelpers.cc
@@ -7,6 +7,7 @@
 
 #include <limits>
 #include <sstream>
+#include <cmath>
 
 #include "eckit/exception/Exceptions.h"
 #include "eckit/geometry/CoordinateHelpers.h"
@@ -16,14 +17,12 @@ namespace eckit::geometry {
 
 //----------------------------------------------------------------------------------------------------------------------
 
-double normalise_angle(double a, const double minimum) {
-    while (a < minimum) {
-        a += 360.;
-    }
-    while (a >= minimum + 360.) {
-        a -= 360.;
-    }
-    return a;
+inline double modulo(const double a, const double b) {
+    return a-b*std::floor(a/b);
+}
+
+double normalise_angle(const double a, const double minimum) {
+    return minimum + modulo(a-minimum, 360.);
 }
 
 //----------------------------------------------------------------------------------------------------------------------