public virtual STuple <Vector, Vector> Apply2(STuple <Vector, Vector> input)
{
Vector inputReal2 = input.Value1;
Vector inputImag2 = input.Value2;
if (inputImag2 == null)
{
inputImag2 = new Vector(inputReal2.Length);
}
Vector outputReal2 = new Vector(inputReal2.Length);
Vector outputImaginary2 = new Vector(inputImag2.Length);
IArrayReadable <float> inputReal = inputReal2;
IArrayReadable <float> inputImag = inputImag2;
IArrayWriteable <float> outputReal = outputReal2;
IArrayWriteable <float> outputImaginary = outputImaginary2;
dft(inputReal, inputImag, outputReal, outputImaginary);
return(new STuple <Vector, Vector>(outputReal2, outputImaginary2));
}
public void dft(IArrayReadable <float> inputReal, IArrayReadable <float> inputImag, IArrayWriteable <float> outputReal, IArrayWriteable <float> outputImaginary)
{
//Xk = sigma(n=0,N-1,xn*e^(-2pi*i*n*k/N)
//e^(i*theta) = cos(theta) + i*sin(theta)
int length = inputReal.Length;
int k;
int n;
float real;
float imag;
float theta;
float twoPiDivLength = (float)(2 * Math.PI / length);
float scale;
float valueReal;
float valueImag;
float ca;
float sa;
SetupLookupTables(length);
float[,] cc = null;
float[,] ss = null;
if (CosineLookupTables.ContainsKey(length))
{
cc = CosineLookupTables[length];
ss = SineLookupTables[length];
}
for (k = 0; k < length; k++)
{
real = 0;
imag = 0;
if (cc == null)
{
scale = k * twoPiDivLength * (IsInverse ? -1 : 1);
for (n = 0; n < length; n++)
{
theta = n * scale;
ca = (float)Math.Cos(theta);
sa = (float)Math.Sin(theta);
valueReal = inputReal[n];
valueImag = inputImag[n];
real += valueReal * ca - valueImag * sa;
imag += valueReal * sa + valueImag * ca;
}
}
else if (IsInverse)
{
for (n = 0; n < length; n++)
{
ca = cc[k, n];
sa = -ss[k, n];
valueReal = inputReal[n];
valueImag = inputImag[n];
real += valueReal * ca - valueImag * sa;
imag += valueReal * sa + valueImag * ca;
}
}
else
{
for (n = 0; n < length; n++)
{
ca = cc[k, n];
sa = ss[k, n];
valueReal = inputReal[n];
valueImag = inputImag[n];
real += valueReal * ca - valueImag * sa;
imag += valueReal * sa + valueImag * ca;
}
}
outputReal[k] = ScaleForInverse(real, length);
outputImaginary[k] = ScaleForInverse(imag, length);
}
}
