fftw_flags

Arguments

[x1;x2;...]

Matrix of string or integers. Entry to switch the method of fft computation for fftw.

a

Integer. Give the current value of the flag of the fftw function.

S

String matrix. Give the string value of the fftw flag.

Description

This function enables the change of the unsigned flags parameter of the fftw_plan_guru_split_dft function that is used in fftw function.

Default value is FFTW_ESTIMATE

Accepted entries are :

• FFTW_MEASURE or 0

• FFTW_DESTROY_INPUT or 1

• FFTW_UNALIGNED or 2

• FFTW_CONSERVE_MEMORY or 4

• FFTW_EXHAUSTIVE or 8

• FFTW_PRESERVE_INPUT or 16

• FFTW_PATIENT or 32

• FFTW_ESTIMATE or 64

• FFTW_ESTIMATE_PATIENT or 128

• FFTW_BELIEVE_PCOST or 256

• FFTW_NO_DFT_R2HC or 512

• FFTW_NO_NONTHREADED or 1024

• FFTW_NO_BUFFERING or 2048

• FFTW_NO_INDIRECT_OP or 4096

• FFTW_ALLOW_LARGE_GENERIC or 8192

• FFTW_NO_RANK_SPLITS or 16384

• FFTW_NO_VRANK_SPLITS or 32768

• FFTW_NO_VRECURSE or 65536

• FFTW_NO_SIMD or 131072

• FFTW_NO_SLOW or 262144

• FFTW_NO_FIXED_RADIX_LARGE_N or 524288

• FFTW_ALLOW_PRUNING or 1048576

Rmk : when using FFTW_MEASURE/FFTW_PATIENT/FFTW_EXHAUSTIVE you must call two times fftw. (first call for initialisation, second and others calls for computation)

Examples

//return the integer value of the flag
fftw_flags()

//change flags
fftw_flags(["FFTW_MEASURE";"FFTW_CONSERVE_MEMORY"]);

//change flags and display current value of fftw flags (both integer and strings)
[a,S]=fftw_flags("FFTW_PATIENT")

See Also

• fftw — Fast fourier transform based on the fftw library