From 2da219ef5e2e977d60c292e185764a71b9d71765 Mon Sep 17 00:00:00 2001
From: david <david>
Date: Thu, 17 Jul 2003 00:26:38 +0000
Subject: [PATCH] Update magvar model before using it to initialize compass
 error.

---
 src/Main/main.cxx | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index 2a8063655..7299f0eed 100644
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -1778,8 +1778,16 @@ static bool fgMainInit( int argc, char **argv ) {
                                 // kludge to initialize mag compass
                                 // (should only be done for in-flight
                                 // startup)
-    fgSetDouble("/instrumentation/heading-indicator/offset-deg",
-                globals->get_mag()->get_magvar() * SGD_RADIANS_TO_DEGREES);
+    // update magvar model
+    globals->get_mag()->update( fgGetDouble("/position/longitude-deg")
+                                * SGD_DEGREES_TO_RADIANS,
+                                fgGetDouble("/position/latitude-deg")
+                                * SGD_DEGREES_TO_RADIANS,
+                                fgGetDouble("/position/altitude-ft")
+                                * SG_FEET_TO_METER,
+                                globals->get_time_params()->getJD() );
+    double var = globals->get_mag()->get_magvar() * SGD_RADIANS_TO_DEGREES;
+    fgSetDouble("/instrumentation/heading-indicator/offset-deg", -var);
 
     // airport = new ssgBranch;
     // airport->setName( "Airport Lighting" );