package fftw3

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Module type Fftw3.SigSource

Precision independent signature for FFTW3 submodules.

Precision

Sourcetype float_elt

Precision of float numbers.

Sourcetype complex_elt

Precision of complex numbers.

Sourceval float : (float, float_elt) Bigarray.kind

Float of the precision of this module. Use this to create precision independent code.

Complex of the precision of this module. Use this to create precision independent code.

Specifying plans

Sourcetype 'a plan

FFTW plan.

Sourcetype c2c

c2c plan usual discrete Fourier transform, from complex to complex

Sourcetype r2c

r2c plan real to complex transform

Sourcetype c2r

c2r plan complex to real transform

Sourcetype r2r

r2r plan real to real transform

Sourcetype dir =
  1. | Forward
  2. | Backward

Direction of the transform — see the FFTW manual.

Sourcetype measure =
  1. | Estimate
    (*

    No measurements are made, use a simple heuristic to pick a (probably sub-optimal) plan quickly.

    *)
  2. | Measure
    (*

    Find an optimized plan by actually computing several FFTs and measuring their execution time.

    *)
  3. | Patient
    (*

    Like Measure, but considers a wider range of algorithms and often produces a "more optimal" plan at the expense of several times longer planning time.

    *)
  4. | Exhaustive
    (*

    Like Patient, but considers an even wider range of algorithms, including many that are thought unlikely to be fast, to produce the most optimal plan but with a substantially increased planning time.

    *)

Planning-rigor flags.

Sourcetype r2r_kind =
  1. | R2HC
    (*

    real to halfcomplex

    *)
  2. | HC2R
    (*

    halfcomplex to real

    *)
  3. | DHT
    (*

    discrete Hartley Transform

    *)
  4. | REDFT00
    (*

    real-even DFT: even around j=0 and even around j=n-1

    *)
  5. | REDFT01
    (*

    real-even DFT: even around j=0 and odd around j=n

    *)
  6. | REDFT10
    (*

    real-even DFT: even around j=-0.5 and even around j=n-0.5

    *)
  7. | REDFT11
    (*

    real-even DFT: even around j=-0.5 and odd around j=n-0.5

    *)
  8. | RODFT00
    (*

    real-odd DFT; odd around j=-1 and odd around j=n

    *)
  9. | RODFT01
    (*

    real-odd DFT; odd around j=-1 and even around j=n-1

    *)
  10. | RODFT10
    (*

    real-odd DFT; odd around j=-0.5 and odd around j=n-0.5

    *)
  11. | RODFT11
    (*

    real-odd DFT; odd around j=-0.5 and even around j=n-0.5

    *)

Real-to-Real transform kinds. The real-even (resp. real-odd) DFT are somtimes called Discrete Cosine Transform (DCT) (resp. Discrete Sine Transform (DST)). Note that the explanations of the various transforms are for an input array of dimension n and C layout (i.e. the input array is input[0..n-1]). The logical size N is N=2(n-1) for REDFT00, N=2(n+1) for RODFT00, and N=2n otherwise. See the FFTW manual for more details.

Sourceexception Failure of string

Exception raised to indicate that a plan could not be created.

Executing plans

Sourceval exec : 'a plan -> unit

exec plan executes the plan on the arrays given at the creation of this plan. This is the normal way to execute any kind of plan.

This function is thread safe (and may run the actual computation on a different core than the main program).

Sourcemodule Guru : sig ... end

Guru execution of plans.

Creating plans

Sourcemodule Genarray : sig ... end

FFT of Bigarray.Genarray.

Sourcemodule Array1 : sig ... end

FFT of Bigarray.Array1.

Sourcemodule Array2 : sig ... end

FFT of Bigarray.Array2.

Sourcemodule Array3 : sig ... end

FFT of Bigarray.Array3.