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Full Discussion: Slow FFT in ksh93 and awk.
Operating Systems OS X (Apple) Slow FFT in ksh93 and awk. Post 303023472 by Corona688 on Monday 17th of September 2018 06:14:05 PM
Old 09-17-2018
Absolutely. I don't post code for people to not use it.

It's a kind of naive implementation though. Usually better to read values from stdin, but knowing how audioscope works I knew you'd need batches. That'd obscure how it really works a bit though. Maybe better as this, people can populate the arrays as they please.

It's not truly an FFT either, just a DFT -- which gives the same result but takes much more time to do so. Notice how it must do N*N loops for N input. FFT accomplishes the same with N log N loops.

Still, I hope it has its uses. And I'm grateful for you writing one in shell. That's the first DFT I've seen written in a language I really understand.

Last edited by Corona688; 09-17-2018 at 07:26 PM..
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ABINIS(1)																 ABINIS(1)

NAME
abinis - Sequential version of ABINIT SYNOPSIS
abinis < input file > log file DESCRIPTION
abinis is an atomic-scale simulation software and is part of the ABINIT project. ABINIT is a package the main program allows one to find the total energy, charge density and electronic structure of systems made of elec- trons and nuclei (molecules and periodic solids) within Density Functional Theory (DFT), using pseudopotentials and a planewave basis. ABINIT also includes options to optimize the geometry according to the DFT forces and stresses, or to perform molecular dynamics simula- tions using these forces, or to generate dynamical matrices, Born effective charges, and dielectric tensors. Excited states can be computed within the Time-Dependent Density Functional Theory (for molecules), or within Many-Body Perturbation Theory (the GW approximation). By default abinis reads an info block from standard input and logs run-time messages to standard output, while writing the results of the simulation to a file specified in the info block. The format of this info block is described in abinit.files(5) . abinis is the sequential version of the ABINIT code, which means that it will run on one processor only. See abinip(1) if you are in- terested in multiprocessor simulations. VERSION
This man page is correct for the version 4.5 of ABINIT. SEE ALSO
abinip(1) , abinit.files(5) . You may also want to visit http://www.abinit.org/ for up-to-date information about ABINIT and its components. BUGS
See the ABINIT known problems page for more details. AUTHOR
This man page has been written and is maintained by Yann Pouillon <pouillon@pcpm.ucl.ac.be>. COPYRIGHT
Copyright (C) 2004 The ABINIT Group. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. NOTES
This man page is part of the ABIDOC project, which aims at improving the conformance of the ABINIT documentation to the highest possible standards. If you would like to participate, please contact Yann Pouillon (see http://www.abinit.org/ for contact information). ABINIS(1)
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