code: public final void normalize() {
  		double norm;
  
  		norm = (this.x*this.x + this.y*this.y + this.z*this.z + this.w*this.w);
  
  		if (norm > 0f) {
  			norm = 1f / Math.sqrt(norm);
  			this.x *= norm;
  			this.y *= norm;
  			this.z *= norm;
  			this.w *= norm;
  		} else {
  			this.x = 0f;
  			this.y = 0f;
  			this.z = 0f;
  			this.w = 0f;
  		}
  	}
docs: Normalizes the value of this quaternion in place.