Microsoft Accelerator (GPU) based Pi Calculation - A C# Port

This is a quick and dirty port.
Microsoft Research Accelerator Project

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Research.DataParallelArrays;

namespace piSharp.cs
{
  class Program
  {
      static void Main(string[] args)
      {
          Random r = new Random();
          // create randomly generated samples in the unit square centered on (0,0)

          int iSize = 1500;
          float[,] x = new float[iSize + 1, iSize + 1];
          // x coordinate
          float[,] y = new float[iSize + 1, iSize + 1];
          // y coordinate
          int i = 0;
          int j = 0;

          // create an x and y arrays of random numbers between 0 and 1
          for (i = 0; i <= iSize - 1; i += 1)            {                for (j = 0; j <= iSize - 1; j += 1)                {                    x[i, j] = (float)r.NextDouble();
                  y[i, j] = (float)r.NextDouble();
              }
          }
          ParallelArrays.InitGPU();

          // make x and y data parallel arrays
          DisposableFloatParallelArray parallelX = new DisposableFloatParallelArray(x);
          DisposableFloatParallelArray parallelY = new DisposableFloatParallelArray(y);

          // center them about (0, 0) with range (-1, 1)
          FloatParallelArray parallelXCentered = default(FloatParallelArray);
          FloatParallelArray parallelYCentered = default(FloatParallelArray);
          parallelXCentered = ParallelArrays.Multiply(ParallelArrays.Subtract(parallelX, 0.5f), 2f);
          parallelYCentered = ParallelArrays.Multiply(ParallelArrays.Subtract(parallelY, 0.5f), 2f);

          // calculate distance of (x,y) from 0, ie. Sqrt(x^2 + y^2)
          FloatParallelArray parallelXSquare = default(FloatParallelArray);
          FloatParallelArray parallelYSquare = default(FloatParallelArray);
          FloatParallelArray parallelDistance = default(FloatParallelArray);
          parallelXSquare = ParallelArrays.Multiply(parallelXCentered, parallelXCentered);
          parallelYSquare = ParallelArrays.Multiply(parallelYCentered, parallelYCentered);
          parallelDistance = ParallelArrays.Sqrt(ParallelArrays.Add(parallelXSquare, parallelYSquare));
          float[,] test = new float[iSize + 1, iSize + 1];
          ParallelArrays.ToArray(parallelDistance, out test);

          // create an array of 1's if distance <> 1
          FloatParallelArray parallelOne = new FloatParallelArray(1f, parallelX.Shape);
          FloatParallelArray parallelZero = new FloatParallelArray(0f, parallelX.Shape);
          FloatParallelArray parallelInCircle = default(FloatParallelArray);

          parallelInCircle = ParallelArrays.Select(ParallelArrays.Subtract(parallelOne, parallelDistance), parallelOne, parallelZero);

          // the number inside the circle is the sum of the entire InCircle array
          FloatParallelArray parallelCountInCircle = default(FloatParallelArray);
          parallelCountInCircle = ParallelArrays.Sum(parallelInCircle);

          float[] inCircle = new float[2];
          ParallelArrays.ToArray(parallelCountInCircle, out inCircle);
          parallelX.Dispose();
          parallelY.Dispose();

          // approximate pi--area of unit circle is pi
          //                 area of square from -1,1 is 4
          // inCircle/(total number of points) == pi/4
          float pi = 0;
          pi = 4 * inCircle[0] / (iSize * iSize);
          System.Console.WriteLine("Pi is approximately " + pi.ToString());
          ParallelArrays.UnInit();

          // Prompt user for exit for running in VS IDE
          System.Console.WriteLine("Press Enter to Exit");
          System.Console.ReadLine();
      }
  }
}

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