/// <summary>
/// Performs a complex-to-real inverse fast fourier transformation.
/// </summary>
/// <seealso cref="http://www.fftw.org/fftw3_doc/One_002dDimensional-DFTs-of-Real-Data.html#One_002dDimensional-DFTs-of-Real-Data"/>
/// <seealso cref="http://www.fftw.org/fftw3_doc/Multi_002dDimensional-DFTs-of-Real-Data.html#Multi_002dDimensional-DFTs-of-Real-Data"/>
public static void IFFT(IPinnedArray <Complex> input, IPinnedArray <double> output, PlannerFlags plannerFlags = PlannerFlags.Default, int nThreads = 1)
{
if ((plannerFlags & PlannerFlags.Estimate) == PlannerFlags.Estimate)
{
using (var plan = FftwPlanRC.Create(output, input, DftDirection.Backwards, plannerFlags, nThreads))
{
plan.Execute();
return;
}
}
using (var plan = FftwPlanRC.Create(output, input, DftDirection.Backwards, plannerFlags | PlannerFlags.WisdomOnly, nThreads))
{
if (plan != null)
{
plan.Execute();
return;
}
}
/// If with <see cref="PlannerFlags.WisdomOnly"/> no plan can be created
/// and <see cref="PlannerFlags.Estimate"/> is not specified, we use
/// a different buffer to avoid overwriting the input
using (var bufferContainer = _bufferPool.RequestBuffer(input.Length * Marshal.SizeOf <Complex>() + MemoryAlignment))
using (var buffer = new AlignedArrayComplex(bufferContainer.Buffer, MemoryAlignment, input.GetSize()))
using (var plan = FftwPlanRC.Create(output, buffer, DftDirection.Backwards, plannerFlags, nThreads))
{
input.CopyTo(plan.BufferComplex);
plan.Execute();
}
}
/// <summary>
/// Initializes a new plan using the provided input and output buffers.
/// These buffers may be overwritten during initialization.
/// </summary>
public static FftwPlanRC Create(IPinnedArray <double> bufferReal, IPinnedArray <Complex> bufferComplex, DftDirection direction, PlannerFlags plannerFlags = PlannerFlags.Default, int nThreads = 1)
{
FftwPlanRC plan = new FftwPlanRC(bufferReal, bufferComplex, bufferReal.Rank, bufferReal.GetSize(), true, direction, plannerFlags, nThreads);
if (plan.IsZero)
{
return(null);
}
return(plan);
}
internal static FftwPlanRC Create(IPinnedArray <double> bufferReal, IPinnedArray <Complex> bufferComplex, int rank, int[] n, DftDirection direction, PlannerFlags plannerFlags, int nThreads)
{
FftwPlanRC plan = new FftwPlanRC(bufferReal, bufferComplex, rank, n, false, direction, plannerFlags, nThreads);
if (plan.IsZero)
{
return(null);
}
return(plan);
}
