public static bool DCTUnitTest()
{
int precisionDigits = 10;
var tolerance = new RealNumber(32 - 64 * precisionDigits, IntegerNumber.One, precisionDigits);
Random random = new Random(1001);
int n = 3 * 5 * 7 * 2 * 2;
var dcti1 = new RealNumber[n];
var dcti2 = new RealNumber[n];
var dcti3 = new RealNumber[n];
for (int i = n; --i >= 0;)
{
dcti1[i] = dcti2[i] = dcti3[i] = new RealNumber(random.NextDouble() * 256 - 128, precisionDigits);
}
dcti2.EvenDCTType2();
SlowDCT2(dcti3);
var maximumError1 = dcti2.GetMaximumError(dcti3) * new RealNumber(n, precisionDigits).GetInverseSqrt();
dcti2.EvenDCTType3();
RealNumber scale = new RealNumber(n, precisionDigits).Inverse();
for (int i = n; --i >= 0;)
{
dcti2[i] *= scale;
}
var maximumError2 = dcti1.GetMaximumError(dcti2);
return(maximumError1 < tolerance && maximumError2 < tolerance);
}