public void ExampleLowpass()
{
int shiftUp = 1000; //1khz
int fade = 2; //8 sample fade.
int halfsize = samplesize / 2;
int kick = frequencies[0].Length * shiftUp / rate;
for (int i = 0; i < sampleCount; i++)
{
for (int j = 0; j < frequencies[i].Length; j++)
{
if (j == 0 || j == halfsize)
{
continue;
}
if (j < halfsize)
{
if (!(j < kick + 1))
{
frequencies[i][j] = 0;
}
}
else
{
if (!(j - halfsize > halfsize - 1 - kick))
{
frequencies[i][j] = 0;
}
}
}
dft.BluesteinInverse(frequencies[i], MathNet.Numerics.IntegralTransforms.FourierOptions.Default);
}
}
public void FourierBluesteinIsReversible(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.Random((u, v) => new Complex(u, v), GetUniform(1), 0x7FFF);
var work = new Complex[samples.Length];
samples.CopyTo(work, 0);
dft.BluesteinForward(work, options);
Assert.IsFalse(work.ListAlmostEqual(samples, 6));
dft.BluesteinInverse(work, options);
AssertHelpers.ListAlmostEqual(samples, work, 10);
}
public void FourierBluesteinMatchesNaiveOnRandomNonPowerOfTwo(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.Random((u, v) => new Complex(u, v), _uniform, 0x7F);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}
public void FourierBluesteinMatchesNaiveOnRandomNonPowerOfTwo(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.Random((u, v) => new Complex(u, v), _uniform, 0x7F);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}
public void FourierBluesteinMatchesNaiveOnRealSineNonPowerOfTwo(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.EquidistantPeriodic(w => new Complex(Math.Sin(w), 0), Constants.Pi2, 0, 14);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}
public void FourierBluesteinMatchesNaiveOnRandomPowerOfTwo([Values(FourierOptions.Default, FourierOptions.Matlab, FourierOptions.NumericalRecipes)] FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.Random((u, v) => new Complex(u, v), _uniform, 0x80);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}
public void FourierBluesteinIsReversible(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
VerifyIsReversibleComplex(
0x7FFF,
1e-12,
s =>
{
dft.BluesteinForward(s, options);
return s;
},
s =>
{
dft.BluesteinInverse(s, options);
return s;
});
}
public void FourierBluesteinIsReversible(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
VerifyIsReversibleComplex(
0x7FFF,
1e-12,
s =>
{
dft.BluesteinForward(s, options);
return(s);
},
s =>
{
dft.BluesteinInverse(s, options);
return(s);
});
}
/// <summary>
/// Applies the inverse Fast Fourier Transform (iFFT) to arbitrary-length sample vectors.
/// </summary>
/// <param name="samples">Sample vector, where the FFT is evaluated in place.</param>
public static void FourierInverse(Complex[] samples)
{
_dft.BluesteinInverse(samples, FourierOptions.Default);
}
public void FourierBluesteinMatchesNaiveOnRealSineNonPowerOfTwo(FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.EquidistantPeriodic(w => new Complex(Math.Sin(w), 0), Constants.Pi2, 0, 14);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}
public void FourierBluesteinMatchesNaiveOnRandomPowerOfTwo([Values(FourierOptions.Default, FourierOptions.Matlab, FourierOptions.NumericalRecipes)] FourierOptions options)
{
var dft = new DiscreteFourierTransform();
var samples = SignalGenerator.Random((u, v) => new Complex(u, v), _uniform, 0x80);
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveForward(s, options),
s => dft.BluesteinForward(s, options));
VerifyMatchesNaiveComplex(
samples,
1e-12,
s => dft.NaiveInverse(s, options),
s => dft.BluesteinInverse(s, options));
}