using System;

namespace Science.Mathematics.VectorCalculus
{
    public class Vector
    {
        protected double[] el;
        protected int n;
	    public int Dimension
		{
			get{return n;}
		}
        public Vector()
        {
        }
        public Vector(Point p)
        {
            el = new double[p.Coordinate.Length];
            for (int k = 0; k < p.Coordinate.Length; k++) 
                el[k] = p.Coordinate[k];
            n = p.Coordinate.Length;
        }
        public Vector(Point p, Point q)
        {
            el = new double[p.Coordinate.Length];
            for (int k = 0; k < p.Coordinate.Length; k++)
                el[k] = q.Coordinate[k] - p.Coordinate[k];
            n = p.Coordinate.Length;
        }
		public Vector(double[] x)
		{
			el = new double[x.Length];
            for (int k = 0; k < x.Length; k++) el[k] = x[k];
            n = x.Length;
		}
        public Vector(int dimension)
        {
            el = new double[dimension];
            n = dimension;
        }
		public double this[int where]
		{
			get{return el[where];}
			set{el[where]=value;}
		}
		public double Norm
		{
			get
			{
				double sq = 0.0;
				foreach(double k in el) sq += k*k;
				return Math.Sqrt(sq);			
			}
		}
        public double Length
        {
            get { return this.Norm; }
        }

		public static Vector operator *(double a, Vector c)
		{
			Vector b = new Vector(c.Dimension);
			for(int k = 0; k < c.Dimension; k++) b[k] = a*c[k];
     		return b;
		}  
		public static Vector operator *(Vector c, double a)
		{
			return a*c;
		}
		public static Vector operator +(Vector a, Vector c)
		{
            Vector b = new Vector(a.Dimension);
            for (int k = 0; k < c.Dimension; k++) 
					b[k] = a[k]+c[k];
			return b;
		}
		public static Vector operator -(Vector a, Vector c)
		{
            Vector b = new Vector(a.Dimension);
            for (int k = 0; k < c.Dimension; k++) 
				b[k] = a[k]-c[k];
			return b;
		}
        public static Vector operator -(Vector c)
        {
            Vector b = new Vector(c.Dimension);
            for (int k = 0; k < c.Dimension; k++)
                b[k] = - c[k];
            return b;
        }
		public static double operator *(Vector a, Vector c)
		{
			double sum = 0.0;
            for (int k = 0; k < a.Dimension; k++) 
			    sum += a[k]*c[k];
			return sum;
		}
        public static Vector operator %(Vector a, Vector b)  // CrossProduct
        {
            Vector c = new Vector(3);
            c[0] = a[1] * b[2] - a[2] * b[1];
            c[1] = a[2] * b[0] - a[0] * b[2];
            c[2] = a[0] * b[1] - a[1] * b[0];
            return c;
        }

        public Vector OrthogonalProjection(Vector on)
        {
            return this*on / on.Norm / on.Norm * on;
        }

        public override string ToString()
        {
            string res = "(";
            for (int i = 0; i < this.Dimension - 1; i++)
            {
                res += this[i].ToString() + ",";
            }
            res += this[this.Dimension - 1].ToString() + ")" + "\r\n";
            return res;
        }
    }
}