amrex::FFT Namespace Reference

Classes
struct	Info
class	LocalR2C
	Local Discrete Fourier Transform. More...
class	OpenBCSolver
	Convolution-based solver for open boundary conditions using Green's functions. More...
struct	Plan
class	Poisson
	Poisson solver for periodic, Dirichlet & Neumann boundaries using FFT. More...
class	PoissonHybrid
	3D Poisson solver for periodic, Dirichlet & Neumann boundaries in the first two dimensions, and Dirichlet & Neumann in the last dimension. The last dimension could have non-uniform mesh. More...
class	PoissonOpenBC
	Poisson solve for Open BC using FFT. More...
class	R2C
	Parallel Discrete Fourier Transform. More...
class	R2X
	Discrete Fourier Transform. More...
class	Stokes
	Stokes solver for periodic domains using FFT. More...

Typedefs
template<typename T = Real, FFT::Direction D = FFT::Direction::both>
using	C2C = R2C< T, D, true >
	FFT between complex data.

Enumerations
enum struct	Direction { forward , backward , both , none }
enum struct	DomainStrategy { automatic , slab , pencil }
enum class	Boundary : int { periodic , even , odd }
enum struct	Kind {   none , r2c_f , r2c_b , c2c_f ,   c2c_b , r2r_ee_f , r2r_ee_b , r2r_oo_f ,   r2r_oo_b , r2r_eo , r2r_oe }

Functions
Boundary_EnumTraits	amrex_get_enum_traits (Boundary)
constexpr int	FastNumPrimeFactors () noexcept
	Return the default factor count used for selecting fast FFT lengths.
int	nextFastLen (int target, int nfactors=FastNumPrimeFactors())
	Return the smallest fast FFT length greater than or equal to target.

Typedef Documentation

C2C

template<typename T = Real, FFT::Direction D = FFT::Direction::both>

using amrex::FFT::C2C = typedef R2C<T, D, true>

FFT between complex data.

Enumeration Type Documentation

Boundary

enum class amrex::FFT::Boundary : int

strong

Enumerator
periodic
even
odd

Direction

enum struct amrex::FFT::Direction

strong

Enumerator
forward
backward
both
none

DomainStrategy

enum struct amrex::FFT::DomainStrategy

strong

Enumerator
automatic
slab
pencil

Kind

enum struct amrex::FFT::Kind

strong

Enumerator
none
r2c_f
r2c_b
c2c_f
c2c_b
r2r_ee_f
r2r_ee_b
r2r_oo_f
r2r_oo_b
r2r_eo
r2r_oe

Function Documentation

amrex_get_enum_traits()

Boundary_EnumTraits amrex::FFT::amrex_get_enum_traits

(

Boundary

)

FastNumPrimeFactors()

constexpr int amrex::FFT::FastNumPrimeFactors ( )

constexprnoexcept

Return the default factor count used for selecting fast FFT lengths.

The default is platform dependent. CUDA currently uses 5; other backends currently use 6. This tuning default may change in the future.

Returns

Default number of prime factors used by FFT::nextFastLen.

nextFastLen()

int amrex::FFT::nextFastLen ( int  target, int  nfactors = FastNumPrimeFactors()  )

inline

Return the smallest fast FFT length greater than or equal to target.

The allowed factors are the first nfactors values from {2, 3, 5, 7, 11, 13}. When nfactors is omitted, FFT::FastNumPrimeFactors() provides a platform-dependent default.

Parameters

target	Minimum requested FFT length. It must be positive.
nfactors	Number of supported prime factors. It must be between 3 and 6.

Returns

A fast FFT length no smaller than target.