fixed NPE bug 1453 in start analysis in case a mark position is not known

java/com.sap.sailing.domain.common/src/com/sap/sailing/domain/common/AbstractPosition.java

@@ -63,13 +63,17 @@ public class AbstractPosition implements Position {
 
     @Override
     public Bearing getBearingGreatCircle(Position p) {
-        double result = Math.atan2(Math.sin(p.getLngRad()-getLngRad()) * Math.cos(p.getLatRad()),
-                Math.cos(getLatRad())*Math.sin(p.getLatRad()) -
-                Math.sin(getLatRad())*Math.cos(p.getLatRad())*Math.cos(p.getLngRad()-getLngRad())) ;
-        if (result < 0) {
-            result = result + 2*Math.PI;
+        Bearing bearing = null;
+        if (p != null) {
+            double result = Math.atan2(Math.sin(p.getLngRad() - getLngRad()) * Math.cos(p.getLatRad()),
+                    Math.cos(getLatRad()) * Math.sin(p.getLatRad()) - Math.sin(getLatRad()) * Math.cos(p.getLatRad())
+                            * Math.cos(p.getLngRad() - getLngRad()));
+            if (result < 0) {
+                result = result + 2 * Math.PI;
+            }
+            bearing = new RadianBearingImpl(result);
         }
-        return new RadianBearingImpl(result);
+        return bearing;
     }
 
     @Override
@@ -123,7 +127,7 @@ public class AbstractPosition implements Position {
     @Override
     public Distance alongTrackDistance(Position pos2, Bearing bearing) {
         double direction = Math.signum(Math.cos(pos2.getBearingGreatCircle(this).getRadians() - bearing.getRadians()));
-        // Test if denominator gets ridiculously small; if so, the cross-track error is about 90° central angle.
+        // Test if denominator gets ridiculously small; if so, the cross-track error is about 90� central angle.
         // This means that the cross-track error is maximized, and that there is no way to determine how far along
         // the great circle described by pos2 and bearing we should travel. This is an exception which will
         // surface as a division-by-zero exception or a NaN result