public WWDecimalFft(int numPoints)
{
if (!IsPowerOfTwo(numPoints) || numPoints < 2)
{
throw new ArgumentException("numPoints must be power of two integer and larger than 2");
}
mNumPoints = numPoints;
mWn = new WWDecimalComplex[mNumPoints];
for (int i = 0; i < mNumPoints; ++i)
{
decimal angle = -2.0M * WWDecimalMath.M_PI * i / mNumPoints;
mWn[i] = new WWDecimalComplex(WWDecimalMath.Cos(angle), WWDecimalMath.Sin(angle));
}
// mNumStage == log_2(mNumPoints)
int t = mNumPoints;
for (int i = 0; 0 < t; ++i)
{
t >>= 1;
mNumStage = i;
}
mBitReversalTable = new uint[mNumPoints];
for (uint i = 0; i < mNumPoints; ++i)
{
mBitReversalTable[i] = BitReversal(mNumStage, i);
}
}
public static void TestCos()
{
for (int i = -360; i <= 720; i += 30)
{
Console.WriteLine("cos({0})={1}", i, WWDecimalMath.Cos(WWDecimalMath.M_2PI * i / 180));
}
}
void Run(ValueType t)
{
// 1024 samples of 44100Hz PCM contains 23 periods of 998.5Hz sine wave
decimal frequency = 23 * WWDecimalMath.M_2PI;
var signalTime = new WWDecimalComplex[LENGTH];
for (int i = 0; i < LENGTH; ++i)
{
decimal r = WWDecimalMath.Cos(frequency * i / LENGTH);
switch (t)
{
case ValueType.VT_Int16:
r = ((int)(r * 32767)) / 32767M;
break;
case ValueType.VT_Int24:
r = (decimal)((int)(r * 8388607) / 8388607M);
break;
case ValueType.VT_Int32:
r = (decimal)((int)(r * Int32.MaxValue) / ((decimal)(Int32.MaxValue)));
break;
case ValueType.VT_Float32:
r = (decimal)((float)r);
break;
case ValueType.VT_Float64:
r = (decimal)((double)r);
break;
case ValueType.VT_Int64:
r = (decimal)(((long)(r * Int64.MaxValue)) / ((decimal)(Int64.MaxValue)));
break;
case ValueType.VT_Decimal:
break;
}
signalTime[i] = new WWDecimalComplex(r, 0);
}
FftSpectrum(signalTime);
Console.WriteLine("Done.");
}