From 042b51287743615df77766a47e0df33e6a3e70ca Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 2 Sep 2021 16:59:53 +1000
Subject: [PATCH] AP_Declination: fixed rounding in mag field

thanks to Angela for noticing this
---
 libraries/AP_Declination/AP_Declination.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_Declination/AP_Declination.cpp b/libraries/AP_Declination/AP_Declination.cpp
index 37dd1ed51c..bd50eaf0fa 100644
--- a/libraries/AP_Declination/AP_Declination.cpp
+++ b/libraries/AP_Declination/AP_Declination.cpp
@@ -37,8 +37,8 @@ bool AP_Declination::get_mag_field_ef(float latitude_deg, float longitude_deg, f
     bool valid_input_data = true;
 
     /* round down to nearest sampling resolution */
-    int32_t min_lat = static_cast<int32_t>(static_cast<int32_t>(latitude_deg / SAMPLING_RES) * SAMPLING_RES);
-    int32_t min_lon = static_cast<int32_t>(static_cast<int32_t>(longitude_deg / SAMPLING_RES) * SAMPLING_RES);
+    int32_t min_lat = static_cast<int32_t>(static_cast<int32_t>(floorf(latitude_deg / SAMPLING_RES)) * SAMPLING_RES);
+    int32_t min_lon = static_cast<int32_t>(static_cast<int32_t>(floorf(longitude_deg / SAMPLING_RES)) * SAMPLING_RES);
 
     /* for the rare case of hitting the bounds exactly
      * the rounding logic wouldn't fit, so enforce it.