private static void RunTrials(int sampleSize, double errorMargin)
{
var q = new Queue <double>();
while (q.Count < sampleSize)
{
q.Enqueue(Randomness.NextSecureDouble());
}
for (int k = 0; k < 1000; k++)
{
// rotate
q.Dequeue();
q.Enqueue(Randomness.NextSecureDouble());
var avg = q.Average();
// Dividing by n−1 gives a better estimate of the population
// standard deviation for the larger parent population than dividing by n,
// which gives a result which is correct for the sample only.
var actual = Math.Sqrt(q.Sum(x => (x - avg) * (x - avg)) / (q.Count - 1));
// see http://stats.stackexchange.com/a/1014/4576
var expected = (q.Max() - q.Min()) / Math.Sqrt(12);
Assert.AreEqual(expected, actual, errorMargin);
}
}
public void ByteArrayComparer_SortRandomUInt32Test()
{
var comparer = new ByteArrayComparer();
var r = Randomness.NextRandom();
var list = new List <byte[]>(1000);
var list2 = new List <uint>(1000);
for (int i = 0; i < 1000; i++)
{
var bytes = new byte[4];
r.NextBytes(bytes);
uint x = ((uint)bytes[0] << 24)
| ((uint)bytes[1] << 16)
| ((uint)bytes[2] << 8)
| bytes[3]
;
list.Add(bytes);
list2.Add(x);
}
list.Sort(comparer);
list2.Sort(); // use default comparer
CollectionAssert.AreEqual(list2, list.Select(bytes => {
uint x = ((uint)bytes[0] << 24)
| ((uint)bytes[1] << 16)
| ((uint)bytes[2] << 8)
| bytes[3]
;
return(x);
}).ToList());
}
public void BitTwiddling_ByteSwapUInt64Test()
{
var r = Randomness.NextRandom();
var bytes = new byte[8];
for (int i = 0; i < 1000; i++)
{
r.NextBytes(bytes);
var reversed = BitConverter.GetBytes(BitConverter.ToUInt64(bytes, 0).ByteSwap());
CollectionAssert.AreEqual(bytes.Reverse().ToArray(), reversed);
}
}
