private double doubleVectorAbs(Vector<Vector<Double>> doubleVector) {
double totalX = 0;
for (Vector<Double> vector : doubleVector) {
totalX += Math.pow(vectorAbs(vector), 2);
}
return Math.sqrt(totalX);
}
/**
* Calculates the unit normal of a particular vector, where the vector is represented by the
* direction and magnitude of the line segment from (0,0) to (p.x, p.y).
*
* @param p
* @return
*/
private static Point2D vectorUnitNormal(Point2D p) {
// if null object passed or if the passed vector has zero length
if (null == p || ((0 == p.getX()) && (0 == p.getY()))) {
return null;
}
// normalise the input "vector"
// 1. get length of vector (Pythagoras)
// 2. divide both x and y by this length
// note: c cannot be 0 as we've already considered zero length input
// vectors above.
double c = Math.sqrt((p.getX() * p.getX()) + (p.getY() * p.getY()));
double nvx = p.getX() / c;
double nvy = p.getY() / c;
// Now rotate (nvx, nvy) by 90 degrees to get the normal for the
// input vector.
// rx = nvx * cos (pi/2) - nvy * sin (pi/2)
// ty = nvx * sin (pi/2) + nvy * cos (pi/2)
// but cos (pi/2) = 0 and sin (pi/2) = 1, so this simplifies
return new Point2D.Float((float) (-1 * nvy), (float) nvx);
}
private double vectorAbs(Vector<Double> vector) {
double totalX = 0;
for (Double x : vector) totalX += Math.pow(x, 2);
return Math.sqrt(totalX);
}
