FFTW

Usage

use FFTW;

Submodules

config param isFFTW_MKL = false

Set this to true if you are using the Intel MKL FFTW wrappers

config param autoInitFFTW_MT = false

Set this config parameter to true to automatically initialize FFTW for thread support, and setup FFTW to generate multi-threaded plans (with the number of threads equal to maxTaskPar in Chapel).

If you keep the default value of false, then call init_FFTW_MT() to initialize thread-support for Chapel.

Note that plan_with_nthreads can be called at any time and changes the number of threads used by plans created after the call.

config param noFFTWsizeChecks = false

Controls execution-time array size checks in the FFTW plan_dft routines (set to true to disable checks).

type fftw_plan

An opaque type used to store and reuse FFTW plans across multiple routines.

type FFTW_Flag = c_uint

Type alias for FFTW flags

type FFTW_Direction = c_int

Type alias for FFT directions

type FFTW_R2R = c_int

Type alias for FFTW R2R type

proc plan_dft(input: [?Din] complex(128), output: [?Dout] complex(128), sign: FFTW_Direction, flags: FFTW_Flag): fftw_plan

Creates a plan for an out-of-place complex-to-complex DFT.

Arguments:
  • input : [] complex(128) – The input array, which can be of any rank
  • output : [] complex(128) – The output array, whose size and shape must match the input array’s
  • sign : FFTW_Direction – FFTW_FORWARD or FFTW_BACKWARD
  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc plan_dft(arr: [] complex(128), sign: FFTW_Direction, flags: FFTW_Flag): fftw_plan

Creates a plan for an in-place complex-to-complex DFT.

Arguments:
  • arr : [] complex(128) – The array to use as the in-place input/output array.
  • sign : FFTW_Direction – FFTW_FORWARD or FFTW_BACKWARD
  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc plan_dft_r2c(input: [?Din] real(64), output: [?Dout] complex(128), flags: FFTW_Flag): fftw_plan

Create a plan for a real-to-complex, out-of-place DFT.

Arguments:
  • input : [] real(64) – The input array, which can be of any rank
  • output : [] complex(128) – The output array, whose size and shape must match the input array’s, except for the leading dimension which should be n/2 + 1, where n is the size of the input array’s leading dimension. See the FFTW documentation for more information.
  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc plan_dft_r2c(realDom: domain, arr: [?D] ?t, flags: FFTW_Flag): fftw_plan

Create a plan for a real-to-complex, in-place DFT.

Arguments:
  • realDom : domain – Describes the indices of the ‘real’ view of the array
  • arr : [] T where T is of type real(64) or complex(128) –

    The array to be used as the in-place input/output array. If passing in an array of real elements, the leading dimension of the array must be padded to store 2(n/2 + 1) elements, where n is the size of the corresponding dimension of realDom. If passing in an array of complex elements, the leading dimension should be (n/2 + 1). See the FFTW documentation for more information.

  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc plan_dft_c2r(input: [?Din] complex(128), output: [?Dout] real(64), flags: FFTW_Flag): fftw_plan

Create a plan for a complex-to-real, out-of-place DFT.

Arguments:
  • input : [] complex(128) –

    The input array, whose size and shape must match the output array’s, except for the leading dimension which should be n/2 + 1, where n is the size of the output array’s leading dimension. See the FFTW documentation for more information.

  • output : [] real(64) – The output array
  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc plan_dft_c2r(realDom: domain, arr: [?D] ?t, flags: FFTW_Flag): fftw_plan

Create a plan for a complex-to-real, in-place DFT.

Arguments:
  • realDom : domain – Describes the indices of the ‘real’ view of the array
  • arr : [] T where T is of type real(64) or complex(128) –

    The array to be used as the in-place input/output array. If passing in an array of real elements, the leading dimension of the array must be padded to store 2(n/2 + 1) elements, where n is the size of the corresponding dimension of realDom. If passing in an array of complex elements, the leading dimension should be (n/2 + 1). See the FFTW documentation for more information.

  • flags : FFTW_Flag – the bitwise-or of any planning-rigor or algorithm-restriction flags that should be used in creating the plan (e.g., FFTW_MEASURE | FFTW_PRESERVE_INPUT)
Returns:

The fftw_plan representing the resulting plan
proc execute(const plan: fftw_plan)

Execute an FFTW plan.

Arguments:plan : fftw_plan – The plan to execute, as computed by a plan_dft*() routine.
proc destroy_plan(plan: fftw_plan)

Destroy an FFTW plan.

Arguments:plan : fftw_plan – The plan to destroy
proc cleanup()

Clean up FFTW overall.

const FFTW_FORWARD: FFTW_Direction

Request a forward transform (i.e., use a negative exponent in the transform).

const FFTW_BACKWARD: FFTW_Direction

Request a backward transform (i.e., use a positive exponent in the transform).

const FFTW_ESTIMATE: FFTW_Flag

Specify that a simple heuristic should be used to pick a plan quickly. This will prevent the input/output arrays from being overwritten during planning.

const FFTW_MEASURE: FFTW_Flag
const FFTW_PATIENT: FFTW_Flag

Specify that FFTW should expend a greater effort finding an optimized plan.

const FFTW_EXHAUSTIVE: FFTW_Flag

Specify that FFTW should expend an even greater effort finding an optimized plan.

const FFTW_WISDOM_ONLY: FFTW_Flag

This is a special planning mode that is useful for querying whether wisdom is available. When using it, the plan is only created when wisdom is available for the given problem; otherwise a null plan is returned. This can be combined with other flags to create a plan if the wisdom available was created in that mode (e.g., FFTW_WISDOM_ONLY | FFTW_PATIENT). For more details on this flag and the previous four, refer to Section 4.3.2 of the FFTW manual

const FFTW_DESTROY_INPUT: FFTW_Flag
const FFTW_PRESERVE_INPUT: FFTW_Flag
const FFTW_UNALIGNED: FFTW_Flag
const FFTW_R2HC: FFTW_R2R

Use the halfcomplex form of array storage

const FFTW_HC2R: FFTW_R2R
const FFTW_DHT: FFTW_R2R

Discrete Hartley Transforms.

const FFTW_REDFT00: FFTW_R2R

Specify the type of discrete cosine and discrete sine transforms to use.

const FFTW_REDFT01: FFTW_R2R
const FFTW_REDFT10: FFTW_R2R
const FFTW_REDFT11: FFTW_R2R
const FFTW_RODFT00: FFTW_R2R
const FFTW_RODFT01: FFTW_R2R
const FFTW_RODFT10: FFTW_R2R
const FFTW_RODFT11: FFTW_R2R
proc init_FFTW_MT()

Initialize the FFTW module to support multithreading. This has the effect of calling the FFTW C routine fftw_init_threads() on all locales, halting the Chapel program if any of the calls generate an error.

proc plan_with_nthreads(nthreads: int = 0)

Register the number of threads to use for multi-threaded FFTW plans on all locales. If fewer than one thread is requested, each locale will default to here.maxTaskPar threads. Note that this routine can be called multiple times, overwriting previous values.

Arguments:nthreads : int – The number of threads to use.
proc cleanup_threads()

Clean up the memory used by FFTW threads on all locales.