AppInventor: Menghitung Jarak dan Arah dari GPS
Sumber: https://sites.google.com/site/appinventor/distance-based-on-lat-long
Menghitung Jarak
Jarak:
distance = sqrt(x^2 + y^2)
Dimana:
x = 69.1 * (lat2 - lat1) y = 69.1 * (lon2 - lon1) * cos(lat1/57.3)
Menghitung Arah
Arah:
β = atan2(X,Y),
Dimana
X = cos θb * sin ∆L Y = cos θa * sin θb – sin θa * cos θb * cos ∆L
Arah Kiblat
PI = 3.1415926535; phiK = 21.422507*PI/180.0; lambdaK = 39.826329*PI/180.0; phi = lat*PI/180.0; lambda = lon*PI/180.0; psi = 180.0/PI*atan2(sin(lambdaK-lambda), cos(phi)*tan(phiK)-sin(phi)*cos(lambdaK-lambda)); return Math.round(psi);
Ref: http://www.islamicsoftware.org/qibla/qibla.html