Digital Compass difficulty

[Badeand]

Hi, can someone see whats wrong with this formula/code? the compas works perfectly for North, south, east, west, but not the values inbetween. its very inaccurate in between.

float Instrument::bearing(QPointF *src, QPointF *dest) {
 
    float dLon = dest->y() - src->y();
 
    float y = sin(dLon) * cos(dest->x());
    float x = cos(src->x()) * sin(dest->x()) - sin(src->x()) * cos(dest->x()) * cos(dLon);
    float brng = atan2(x, y); 
 
 
    qDebug() << brng << "BRNG !!!!!!!!!!!!!!!!!!!";
    brng *= 180/(4.0*atan(1.0));                            // 180/pi
    int deg = (((int)brng + 360) % 360);
 
    return deg;

float Instrument::bearing(QPointF *src, QPointF *dest) {

    float dLon = dest->y() - src->y();

    float y = sin(dLon) * cos(dest->x());
    float x = cos(src->x()) * sin(dest->x()) - sin(src->x()) * cos(dest->x()) * cos(dLon);
    float brng = atan2(x, y); 


    qDebug() << brng << "BRNG !!!!!!!!!!!!!!!!!!!";
    brng *= 180/(4.0*atan(1.0));                            // 180/pi
    int deg = (((int)brng + 360) % 360);

    return deg;

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Please help =)

thanks,
Badeand

---

Added after 49 minutes:

Sorry guys I fixed it =)

This did the trick:

float Instrument::bearing(QPointF *src, QPointF *dest) {
 
 
    qreal y = dest->y() - src->y();
    qreal x = (dest->x() - src->x());
    qreal brng = atan2(x, y);
 
 
    qDebug() << brng << "BRNG !!!!!!!!!!!!!!!!!!!";
    brng *= 180/(4.0*atan(1.0));                            // 180/pi
    int deg = (((int)brng + 360) % 360);
 
    return deg;
}

float Instrument::bearing(QPointF *src, QPointF *dest) {


    qreal y = dest->y() - src->y();
    qreal x = (dest->x() - src->x());
    qreal brng = atan2(x, y);


    qDebug() << brng << "BRNG !!!!!!!!!!!!!!!!!!!";
    brng *= 180/(4.0*atan(1.0));                            // 180/pi
    int deg = (((int)brng + 360) % 360);

    return deg;
}

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love,
Badeand

[Rachol]

Due to the new functionality of the forum showing on the main page posts that were not replied (that means "not solved"), I assume that this one doesn't really belong there and therefore I write a post reply in order to make it rest in peace