private void getPxxFx(ComplexArray signal, double samplingRate, out DoubleArray Pxx, out DoubleArray Fx)
{
//Implements Matlab's PWelch. Same as [Pxx, Fx] = pwelch(x, w, 0, nfft, Fs), where x = signal, w is calculated below, nfft = signal.count, Fs = samplingRate (hz)
int Nx = signal.Count;
DoubleArray w = DoubleArray.From(hamming(Nx));
double std = w.Std();
double mean = w.Mean();
ComplexArray xw = signal.ElementMultiply(w);
int nfft = Nx;
ComplexArray X = FFTComp.FFTComplex(xw);
DoubleArray absX = X.Abs();
DoubleArray mx = absX.ElementMultiply(absX);
DoubleArray wt = w.Transpose();
double res = w.Multiply(wt)[0];
mx = mx.Divide(res);
int numUniquePts = nfft / 2 + 1;
Slice slice = new Slice(0, numUniquePts - 1);
mx = mx.GetSlice(slice);
double temp1 = mx[0];
double temp2 = mx[mx.Count - 1];
mx = mx.Multiply(2);
mx[0] = temp1;
mx[mx.Count - 1] = temp2;
Pxx = mx.Divide(samplingRate);
Fx = getFx(numUniquePts, samplingRate, nfft);
w.Dispose();
absX.Dispose();
mx.Dispose();
wt.Dispose();
}
private void GetPxxFx(ComplexArray signal, out DoubleArray Pxx, out DoubleArray Fx)
{
ComplexArray X = FFTComp.FFTComplex(signal);
Pxx = X.Abs();
Fx = GetFx(signal.Length);
X.Dispose();
}