Scilab Function
Last update : 25/10/2006

fftw_flags - set computation method of fast fourier transform of the fftw function

Calling Sequence

[a,[S]]=fftw_flags([x1;x2;...])

Parameters

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 ,   fftw_norm ,   fftw_inplace ,   pushfftw_plan ,   freefftw_plan ,