public static void Investigations()
{
double geosyncOrbitR = 42000.0; // Real example, approximate geosynchronous orbit in km
double oneMillimeter = 1.0 / 1000.0 / 1000.0; // One mm in kilometers
Console.WriteLine("=========== Geosync Orbit plus 1/3 millimeter (and smaller) in kilometers ==========");
Console.WriteLine(" Objective is to have fractions of a millimeter correctly accumulate over many additions\n");
double large = geosyncOrbitR;
double small = oneMillimeter / 3.0;
Console.WriteLine("large: {0}, log10(large): {1:G5}\n", large, Math.Log10(Math.Abs(large)));
for (int i = 0; i < 200; i++)
{
Console.WriteLine("large + small ({0,22:G17}) = {1,22:G17} - sig digits in calc: {2}, log10(small): {3,7:G5}, logs difference: {4,6:G5} ({5}) (CAP V2: {6}, V3: {7})",
small, large + small, DecimalAdditionPrecision(large, small), Math.Log10(Math.Abs(small)),
Math.Log10(Math.Abs(large)) - Math.Log10(Math.Abs(small)), FloatingPointUtil.AdditionMagnitudeDifference(large, small),
FloatingPointUtil.CheckAdditionPrecisionV2(large, small), FloatingPointUtil.CheckAdditionPrecisionV3(large, small));
if (large + small == large)
{
break;
}
small *= 0.1;
}
}
public static void RunTest(long iterations)
{
Stopwatch stopwatch = new Stopwatch();
long loopTime, randomGenerationTime, additionTime, checkPrecisionTimeV1, checkPrecisionTimeV2, checkPrecisionTimeV3;
stopwatch.Start();
for (long i = 0; i < iterations;)
{
i++;
}
loopTime = stopwatch.ElapsedMilliseconds;
Double[] randomA = new Double[iterations];
Double[] randomB = new Double[iterations];
Random random = new Random();
stopwatch.Reset(); stopwatch.Start();
for (long i = 0; i < iterations; i++)
{
randomA[i] = random.NextDouble();
randomB[i] = random.NextDouble();
}
randomGenerationTime = stopwatch.ElapsedMilliseconds;
double sum;
stopwatch.Reset(); stopwatch.Start();
for (long i = 0; i < iterations; i++)
{
sum = randomA[i] + randomB[i];
}
additionTime = stopwatch.ElapsedMilliseconds;
bool result;
stopwatch.Reset(); stopwatch.Start();
for (long i = 0; i < iterations; i++)
{
result = FloatingPointUtil.CheckAdditionPrecisionV1(randomA[i], randomB[i]);
}
checkPrecisionTimeV1 = stopwatch.ElapsedMilliseconds;
stopwatch.Reset(); stopwatch.Start();
for (long i = 0; i < iterations; i++)
{
result = FloatingPointUtil.CheckAdditionPrecisionV2(randomA[i], randomB[i]);
}
checkPrecisionTimeV2 = stopwatch.ElapsedMilliseconds;
stopwatch.Reset(); stopwatch.Start();
for (long i = 0; i < iterations; i++)
{
result = FloatingPointUtil.CheckAdditionPrecisionV3(randomA[i], randomB[i]);
}
checkPrecisionTimeV3 = stopwatch.ElapsedMilliseconds;
Console.WriteLine("Performance Test of CheckAdditionPrecision() - running {0:N0} iterations", iterations);
Console.WriteLine("Times in ms:");
Console.WriteLine(" Empty loop: {0:N0}", loopTime);
Console.WriteLine(" Random number generation: {0:N0}, net: {1:N0}", randomGenerationTime, randomGenerationTime - loopTime);
Console.WriteLine(" Addition: {0:N0}, net: {1:N0}", additionTime, additionTime - loopTime);
Console.WriteLine(" CAP V1(): {0:N0}, net: {1:N0}", checkPrecisionTimeV1, checkPrecisionTimeV1 - loopTime);
Console.WriteLine(" CAP V2(): {0:N0}, net: {1:N0}", checkPrecisionTimeV2, checkPrecisionTimeV2 - loopTime);
Console.WriteLine(" CAP V3(): {0:N0}, net: {1:N0}", checkPrecisionTimeV3, checkPrecisionTimeV3 - loopTime);
Console.WriteLine("CheckAdditionPrecisionV3() takes {0:N2} times longer than addition", (checkPrecisionTimeV3 - loopTime) / (additionTime - loopTime));
Console.WriteLine("CheckAdditionPrecisionV3() runs in {0:N2}% time of original version",
((float)(checkPrecisionTimeV3 - loopTime) / (float)(checkPrecisionTimeV1 - loopTime)) * 100.0f);
}
