public void Complex_Inverse_Mix()
{
const int numSamples = 32;
const int length = 2 * numSamples;
double[] data = new double[length];
for (int i = 0; i < length; i += 2)
{
double z = (double)(i - numSamples) / numSamples;
data[i] = 1.0 / ((z * z) + 1.0);
data[i + 1] = z / ((z * z) + 1.0);
}
data[1] = 0.0; // periodic continuation; force odd
_cft.Convention = TransformationConvention.Matlab;
_cft.TransformForward(data);
ComplexTestImagZero(data);
/* Compare With MATLAB:
* samples_t = 1.0i * ([-16:1:15] ./ 16) ./ (([-16:1:15] ./ 16) .^ 2 + 1.0)
+ 1.0 ./ (([-16:1:15] ./ 16) .^ 2 + 1.0)
+ samples_t(1) = real(samples_t(1))
+ samples_f = fft(samples_t)
*/
Assert.That(data[0 * 2], NumericIs.AlmostEqualTo(25.128, 0.001), "MATLAB 1");
Assert.That(data[1 * 2], NumericIs.AlmostEqualTo(-11.118, 0.001), "MATLAB 2");
Assert.That(data[2 * 2], NumericIs.AlmostEqualTo(-2.7838, 0.0001), "MATLAB 3");
Assert.That(data[6 * 2], NumericIs.AlmostEqualTo(-0.80124, 0.00001), "MATLAB 7");
Assert.That(data[7 * 2], NumericIs.AlmostEqualTo(-0.64953, 0.00001), "MATLAB 8");
Assert.That(data[8 * 2], NumericIs.AlmostEqualTo(-0.53221, 0.00001), "MATLAB 9");
Assert.That(data[13 * 2], NumericIs.AlmostEqualTo(-0.1689, 0.0001), "MATLAB 14");
Assert.That(data[14 * 2], NumericIs.AlmostEqualTo(-0.1158, 0.0001), "MATLAB 15");
Assert.That(data[15 * 2], NumericIs.AlmostEqualTo(-0.065071, 0.00001), "MATLAB 16");
Assert.That(data[20 * 2], NumericIs.AlmostEqualTo(0.18904, 0.0001), "MATLAB 21");
Assert.That(data[21 * 2], NumericIs.AlmostEqualTo(0.2475, 0.0001), "MATLAB 22");
Assert.That(data[22 * 2], NumericIs.AlmostEqualTo(0.31196, 0.00001), "MATLAB 23");
Assert.That(data[29 * 2], NumericIs.AlmostEqualTo(1.4812, 0.0001), "MATLAB 30");
Assert.That(data[30 * 2], NumericIs.AlmostEqualTo(2.1627, 0.0001), "MATLAB 31");
Assert.That(data[31 * 2], NumericIs.AlmostEqualTo(3.8723, 0.0001), "MATLAB 32");
_cft.TransformBackward(data);
// Compare with original samples
for (int i = 0; i < length; i += 2)
{
double z = (double)(i - numSamples) / numSamples;
Assert.That(data[i], NumericIs.AlmostEqualTo(1.0 / ((z * z) + 1.0), 0.00001), "Inv: Real: " + i);
Assert.That(data[i + 1], NumericIs.AlmostEqualTo(i == 0 ? 0.0 : z / ((z * z) + 1.0), 0.00001), "Inv: Imag: " + i);
}
}
public static void IFFT(Complex[] xdata, int m)
{
var temp = new MathNet.Numerics.Complex[(int)Math.Pow(2, m)];
for (int i = 0; i < temp.Length; i++)
{
temp[i].Real = xdata[i].Real;
temp[i].Imag = xdata[i].Imag;
}
cft.TransformBackward(temp);
for (int i = 0; i < temp.Length; i++)
{
xdata[i].Real = temp[i].Real;
xdata[i].Imag = temp[i].Imag;
}
}