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Using generics for calculations

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11 Oct 20046 min read 517K   3.2K   214  
Performing calculations with generic types is not as easy it seems. This article shows how to do it.
// Copyright (c) 2004, R�diger Klaehn
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
// 
//    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
//    * Neither the name of lambda computing nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
using System;
using System.Collections.Generic;

namespace Lambda.Generic.Arithmetic.Test
{
    using System.Drawing;
    using System.Threading;
    using PointG = Point<int, IntMath>;
    using SizeG = Size<int, IntMath>;
    using PointFG = Point<float, FloatMath>;
    using SizeFG = Size<float, FloatMath>;
    using PointDG = Point<double, DoubleMath>;
    using SizeDG = Size<double, DoubleMath>;
    using PointDecG = Point<decimal, DecimalMath>;
    using SizeDecG = Size<decimal, DecimalMath>;

    public class GenericArithmeticsTest
    {
        private static List<int> list;
        static GenericArithmeticsTest()
        {
            list = new List<int>(1000000);
            for (int i = 0; i < 1000000; i++)
                list.Add(i / 100000);
        }
        public static object TestPoint()
        {
            int sum = 0;
            for (Point a = new Point(0, 0); a.X < 1000; a += new Size(1, 0))
                for (Point b = a; b.Y < 1000; b += new Size(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestPointG()
        {
            int sum = 0;
            for (PointG a = new PointG(0, 0); a.X < 1000; a += new SizeG(1, 0))
                for (PointG b = a; b.Y < 1000; b += new SizeG(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestPointF()
        {
            float sum = 0;
            for (PointF a = new PointF(0, 0); a.X < 1000; a += new SizeF(1, 0))
                for (PointF b = a; b.Y < 1000; b += new SizeF(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestPointFG()
        {
            float sum = 0;
            for (PointFG a = new PointFG(0, 0); a.X < 1000; a += new SizeFG(1, 0))
                for (PointFG b = a; b.Y < 1000; b += new SizeFG(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestPointDG()
        {
            double sum = 0;
            for (PointDG a = new PointDG(0, 0); a.X < 1000; a += new SizeDG(1, 0))
                for (PointDG b = a; b.Y < 1000; b += new SizeDG(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestPointDecG()
        {
            decimal sum = 0;
            for (PointDecG a = new PointDecG(0, 0); a.X < 1000; a += new SizeDecG(1, 0))
                for (PointDecG b = a; b.Y < 1000; b += new SizeDecG(0, 1))
                    sum += b.X + b.Y;
            return sum;
        }
        public static object TestListSigma()
        {
            int avg = 0;
            for (int i = 0; i < list.Count; i++)
                avg += list[i];
            avg /= list.Count;
            int rms = 0;
            for (int i = 0; i < list.Count; i++)
            {
                int d = list[i] - avg;
                rms += d * d;
            }
            return (int)Math.Sqrt(rms / list.Count);
        }
        public static object TestListSigmaG()
        {
            int avg;
            return Lists<int, IntMath>.Sigma(list, out avg);
        }
        public static object TestListSigmaG2()
        {
            Signed<int,IntMath> avg = 0;
            for (int i = 0; i < list.Count; i++)
                avg += list[i];
            avg /= list.Count;
            Signed<int, IntMath> rms = 0;
            for (int i = 0; i < list.Count; i++)
            {
                Signed<int, IntMath> d = list[i] - avg;
                rms += d * d;
            }
            return (int)Math.Sqrt(rms / list.Count);
        }
        public static object TestListSigmaG3()
        {
            int avg;
            return Lists<int, CheckedIntMath>.Sigma(list, out avg);
        }
        public delegate object TestDelegate();
        public static void Benchmark(TestDelegate testMethod)
        {
            ThreadPriority p = Thread.CurrentThread.Priority;
            try
            {
#if(!DEBUG)
                Thread.CurrentThread.Priority = ThreadPriority.Highest;
#endif
                DateTime time0, time1, endtime;
                time0 = DateTime.Now;
                time1 = time0 + new TimeSpan(0, 0, 1);
                //for the JIT
                while ((endtime = DateTime.Now) < time1)
                    testMethod();

                int i = 0;
                time0 = DateTime.Now;
                time1 = time0 + new TimeSpan(0, 0, 5);
                //this is the real test. Everything should be JITed by now.
                for (i = 0; (endtime = DateTime.Now) < time1; i++)
                    testMethod();
                TimeSpan deltat = new TimeSpan((endtime.Ticks - time0.Ticks) / i);

                Console.WriteLine(
                    "Method {0} took {1} ",
                    testMethod.Method.Name,
                    deltat);
            }
            finally
            {
                Thread.CurrentThread.Priority = p;
            }
        }
        public static void Main()
        {
#if(DEBUG)
                    Console.WriteLine("Warning: benchmarking in debug mode will not produce meaningful results!");
#endif
            Console.WriteLine("Non-generic standard deviation of 1000000 int elements");
            Benchmark(TestListSigma);
            Console.WriteLine("Generic standard deviation of 1000000 int elements");
            Benchmark(TestListSigmaG);
            Console.WriteLine("Generic standard deviation of 1000000 int elements using wrapper structs");
            Benchmark(TestListSigmaG2);
            Console.WriteLine("Generic standard deviation of 1000000 int elements using overflow checks");
            Benchmark(TestListSigmaG3);
            Console.WriteLine("Non-generic System.Drawing.Point operations");
            Benchmark(TestPoint);
            Console.WriteLine("Generic Point<int> operations");
            Benchmark(TestPointG);
            Console.WriteLine("Non-generic System.Drawing.PointF operations");
            Benchmark(TestPointF);
            Console.WriteLine("Generic Point<float> operations");
            Benchmark(TestPointFG);
            Console.WriteLine("Generic Point<double> operations");
            Benchmark(TestPointDG);
            Console.WriteLine("Generic Point<decimal> operations");
            Benchmark(TestPointDecG);
            Console.ReadLine();
        }
    }
}

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Written By
Web Developer
Germany Germany
Rüdiger Klaehn works as freelance developer in the space industry. He is very interested in functional programming languages and hopes that .NET will lead to a more widespread adoption in the industry.

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