C# Vector Range Example

using System;

using CenterSpace.NMath.Core;

namespace CenterSpace.NMath.Examples.CSharp
{
  /// <summary>
  /// A .NET example in C# showing how to use the indexing class Range with the vector classes.
  /// </summary>
  public class VectorRangeExample
  {
    static void Main( string[] args )
    {
      int length = 10;

      Console.WriteLine();

      var u = new DoubleVector( length, 0, 1 );
      Console.WriteLine( "u = {0}", u.ToString() ); // u = [0 1 2 3 4 5 6 7 8 9]

      // Last five elements of the vector u:
      DoubleVector uLast5 = u[new Range( 5, length - 1 )];
      Console.WriteLine( "uLast5 = {0}", uLast5.ToString() ); // uLast5 = [5 6 7 8 9]

      // Could also get this by specifying all elements from the 6th to the end using
      // the End value from the Position enum
      uLast5 = u[new Range( 5, Position.End )];
      Console.WriteLine( "uLast5 = {0}", uLast5.ToString() ); // uLast5 = [5 6 7 8 9]

      // You can use negative strides too. Here is the vector u, reversed.
      DoubleVector uRev = u[new Range( length - 1, Position.Start, -1 )];
      Console.WriteLine( "uRev = {0}", uRev.ToString() ); // uRev = [9 8 7 6 5 4 3 2 1 0]

      // Notice that when you create a new DoubleVector using the Range or Slice class,
      // you are creating a different "view" of the vectors data. That is, the 
      // DoubleVector instance returned by the indexing operator taking a Range object,
      // and the DoubleVector instance being indexed share the same data:
      uRev[0] = 0;
      Console.WriteLine( "uRev = {0}", uRev.ToString() ); // uRev = [0 8 7 6 5 4 3 2 1 0]
      Console.WriteLine( "u = {0}", u.ToString() ); // u = [0 1 2 3 4 5 6 7 8 0]

      // Finally, we use the DoubleVector method Set(Range) to change the contents of u
      // to alternate values 0 and 1
      var evenElts = new Range( 0, Position.End, 2 );
      var oddElts = new Range( 1, Position.End, 2 );
      u.Set( evenElts, 0 );
      u.Set( oddElts, 1 );
      Console.WriteLine( "u = {0}", u.ToString() ); // u = [0 1 0 1 0 1 0 1 0 1]

      Console.WriteLine();
      Console.WriteLine( "Press Enter Key" );
      Console.Read();

    } // Main

  }// class

}// namespace