Difference between revisions of "Fftdiff.m"

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     kern=fftdiff(order,npoints,dx)
 
     kern=fftdiff(order,npoints,dx)
  
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==Arguments==
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==Parameters==
  
 
       order  - order of the derivative
 
       order  - order of the derivative
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==See also==
 
==See also==
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[[fdmat.m]], [[fdvec.m]], [[fourlap.m]], [[fourdif.m]]
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[[fdmat.m]], [[fdvec.m]], [[fourlap.m]], [[fourdif.m]], [[acomm.m]], [[arnoldi.m]], [[atranspose.m]], [[aux_mat.m]], [[binpack.m]], [[cheap_norm.m]], [[cheb_coeff.m]], [[clean_up.m]], [[dirdiff.m]], [[eigenfields.m]], [[expdrop.m]], [[expmint.m]], [[expmint2.m]], [[frob_chop.m]], [[gaussfun.m]], [[hdot.m]], [[herm_spline.m]], [[jacobianest.m]], [[keep_rank.m]], [[krondelta.m]], [[kronm_new.m]], [[logfactorial.m]], [[lorentzcon.m]], [[lorentzfun.m]], [[md5_hash.m]], [[mprealloc.m]], [[remncomm.m]], [[remtrace.m]], [[rspert.m]], [[rspt_eig.m]], [[snormpdf.m]], [[svd_shrink.m]], [[tikhoind.m]], [[tikhonov.m]], [[trapdiff.m]], [[unit_oper.m]], [[unit_state.m]], [[vvpert.m]], [[Kernel_utilities]]
  
 
''Version 2.1, authors: [[Ilya Kuprov]]''
 
''Version 2.1, authors: [[Ilya Kuprov]]''

Latest revision as of 19:36, 6 June 2026

Spectral differentiation kernel. Differentiation corresponds to multiplication in the Fourier domain. This function generates the multiplier.

Syntax

    kern=fftdiff(order,npoints,dx)

Parameters

      order   - order of the derivative

      npoints - number of points in the grid

      dx      - grid step length

Outputs

      kern - a vector that is to be used for accurate
             numerical differentiation of periodic real
             signals in the following way:

              derivative=real(ifft(fft(signal).*kern));

Notes

Periodic boundary conditions.

See also

fdmat.m, fdvec.m, fourlap.m, fourdif.m, acomm.m, arnoldi.m, atranspose.m, aux_mat.m, binpack.m, cheap_norm.m, cheb_coeff.m, clean_up.m, dirdiff.m, eigenfields.m, expdrop.m, expmint.m, expmint2.m, frob_chop.m, gaussfun.m, hdot.m, herm_spline.m, jacobianest.m, keep_rank.m, krondelta.m, kronm_new.m, logfactorial.m, lorentzcon.m, lorentzfun.m, md5_hash.m, mprealloc.m, remncomm.m, remtrace.m, rspert.m, rspt_eig.m, snormpdf.m, svd_shrink.m, tikhoind.m, tikhonov.m, trapdiff.m, unit_oper.m, unit_state.m, vvpert.m, Kernel_utilities

Version 2.1, authors: Ilya Kuprov