@Override
public final void compute() {
int size = geoList.size();
if (!geoList.isDefined() || size <= 1) {
g.setUndefined();
return;
}
double sigmax = 0;
double sigmay = 0;
double sigmaxx = 0;
// double sigmayy=0; not needed
double sigmaxy = 0;
for (int i = 0; i < size; i++) {
GeoElement geo = geoList.get(i);
if (geo.isGeoPoint()) {
double x;
double y;
if (geo.isGeoElement3D()) {
Coords coords = ((GeoPointND) geo).getInhomCoordsInD3();
if (!Kernel.isZero(coords.getZ())) {
g.setUndefined();
return;
}
x = coords.getX();
y = coords.getY();
} else {
double xy[] = new double[2];
((GeoPoint) geo).getInhomCoords(xy);
x = xy[0];
y = xy[1];
}
sigmax += x;
sigmay += y;
sigmaxx += x * x;
sigmaxy += x * y;
// sigmayy+=y*y; not needed
} else {
g.setUndefined();
return;
}
}
// y on x regression line
// (y - sigmay / n) = (Sxx / Sxy)*(x - sigmax / n)
// rearranged to eliminate all divisions
g.x = size * sigmax * sigmay - size * size * sigmaxy;
g.y = size * size * sigmaxx - size * sigmax * sigmax;
g.z = size * sigmax * sigmaxy - size * sigmaxx * sigmay; // (g.x)x +
// (g.y)y +
// g.z = 0
}
/** Calls doRemove() for all output objects of this algorithm except for keepGeo. */
@Override
public void removeOutputExcept(GeoElement keepGeo) {
for (int i = 0; i < super.getOutputLength(); i++) {
GeoElement geo = super.getOutput(i);
if (geo != keepGeo) {
if (geo.isGeoPoint()) {
removePoint(geo);
} else {
geo.doRemove();
}
}
}
}