From 91b2b48fd89def9008767749a5e0c05c7211f6fc Mon Sep 17 00:00:00 2001
From: rmackay9 <rmackay9@yahoo.com>
Date: Sun, 18 Mar 2012 12:08:45 +0900
Subject: [PATCH] ArduCopter - bug fix to calc_XY_velocity (was using
 uninitialised last_longitutde and last_latitude for speed calculations)

---
 ArduCopter/navigation.pde | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ArduCopter/navigation.pde b/ArduCopter/navigation.pde
index 44aa6aade7..221f665151 100644
--- a/ArduCopter/navigation.pde
+++ b/ArduCopter/navigation.pde
@@ -50,6 +50,12 @@ static void calc_XY_velocity(){
 	// y_GPS_speed positve = Up
 	// x_GPS_speed positve = Right
 
+	// initialise last_longitude and last_latitude
+	if( last_longitude == 0 && last_latitude == 0 ) {
+		last_longitude = g_gps->longitude;
+		last_latitude = g_gps->latitude;
+	}
+
 	// this speed is ~ in cm because we are using 10^7 numbers from GPS
 	float tmp = 1.0/dTnav;