/**
* get the angle between this and other
*
* @param other
* @return
*/
public double getAngleBetween(Vector other) {
// make sure this and other share a point
// and that point is P1
if (!this.getP1().equals(other.getP1())) {
// see if they share any point
if (other.getP2().equals(this.getP1())) {
// reverse other
other = other.reverse();
} else {
throw new IllegalArgumentException("Vectors do not meet up");
}
}
double dotProduct = this.dot(other);
double thisMag = this.getMagnitude();
double otherMag = other.getMagnitude();
return Math.acos(dotProduct / (thisMag * otherMag));
// Vector thisUnit = this.getUnitVector();
// Vector otherUnit = other.getUnitVector();
// return Math.atan2(otherUnit.getY2(), otherUnit.getX2()) - Math.atan2(thisUnit.getY2(),
// thisUnit.getX2());
// return Math.acos(arg0)
}
public Vector add(Vector addVector) {
// basically, we can do this graphically
// move the addVector so that it starts at our end
// then make a vector from our start to the end of the other vector
Vector movedVect = addVector.moveTo(this.getP2());
return new Vector(this.getP1(), movedVect.getP2());
}