source: branches/2925_AutoDiffForDynamicalModels/HeuristicLab.Problems.DynamicalSystemsModelling/3.3/Vector.cs @ 16398

using System;
using System.Diagnostics;

namespace HeuristicLab.Problems.DynamicalSystemsModelling {
  public class Vector {
    public readonly static Vector Zero = new Vector(new double[0]);

    public static Vector operator +(Vector a, Vector b) {
      if (a == Zero) return b;
      if (b == Zero) return a;
      Debug.Assert(a.arr.Length == b.arr.Length);
      var res = new double[a.arr.Length];
      for (int i = 0; i < res.Length; i++)
        res[i] = a.arr[i] + b.arr[i];
      return new Vector(res);
    }

    public static Vector operator -(Vector a, Vector b) {
      if (b == Zero) return a;
      if (a == Zero) return -b;
      Debug.Assert(a.arr.Length == b.arr.Length);
      var res = new double[a.arr.Length];
      for (int i = 0; i < res.Length; i++)
        res[i] = a.arr[i] - b.arr[i];
      return new Vector(res);
    }
    public static Vector operator -(Vector v) {
      if (v == Zero) return Zero;
      for (int i = 0; i < v.arr.Length; i++)
        v.arr[i] = -v.arr[i];
      return v;
    }

    public static Vector operator *(double s, Vector v) {
      if (v == Zero) return Zero;
      if (s == 0.0) return Zero;
      var res = new double[v.arr.Length];
      for (int i = 0; i < res.Length; i++)
        res[i] = s * v.arr[i];
      return new Vector(res);
    }

    public static Vector operator *(Vector v, double s) {
      return s * v;
    }
    public static Vector operator *(Vector u, Vector v) {
      if (v == Zero) return Zero;
      if (u == Zero) return Zero;
      var res = new double[v.arr.Length];
      for (int i = 0; i < res.Length; i++)
        res[i] = u.arr[i] * v.arr[i];
      return new Vector(res);
    }
    public static Vector operator /(double s, Vector v) {
      if (s == 0.0) return Zero;
      if (v == Zero) throw new ArgumentException("Division by zero vector");
      var res = new double[v.arr.Length];
      for (int i = 0; i < res.Length; i++)
        res[i] = 1.0 / v.arr[i];
      return new Vector(res);
    }
    public static Vector operator /(Vector v, double s) {
      return v * 1.0 / s;
    }

    public static Vector Sin(Vector s) {
      var res = new double[s.arr.Length];
      for (int i = 0; i < res.Length; i++) res[i] = Math.Sin(s.arr[i]);
      return new Vector(res);
    }
    public static Vector Cos(Vector s) {
      var res = new double[s.arr.Length];
      for (int i = 0; i < res.Length; i++) res[i] = Math.Cos(s.arr[i]);
      return new Vector(res);
    }

    public double this[int idx] {
      get {
        if (this == Vector.Zero) return 0.0;
        else return arr[idx];
      }
      set {
        if (this == Vector.Zero) throw new InvalidOperationException();
        else arr[idx] = value;
      }
    }

    public int Length {
      get {
        if (this == Vector.Zero) throw new InvalidOperationException();
        else return arr.Length;
      }
    }

    private readonly double[] arr; // backing array;

    public Vector(double[] v) {
      this.arr = v;
    }

    public void CopyTo(double[] target) {
      Debug.Assert(arr.Length <= target.Length);
      Array.Copy(arr, target, arr.Length);
    }
  }
}