[CP2K:4255] Poisson Solver's requirement for FFTSG library

JingQiang gohjin... at gmail.com
Wed Jan 23 09:18:51 CET 2013


Hi,

Thanks for the remark. Even though I have indicated that I would need 
preferred FFT library as FFTSG: 
GLOBAL| Preferred FFT library                                             
FFTSG

But I noticed that in my output file, I got this warning:
WARNING : FFT library FFTSG is not available  Trying FFTW3

The calculations can be completed without any other issue. Does it mean 
that the wavelet Poisson solver still use the FFTST, but the other parts of 
the codes rely on FFTW3 libraries? Thanks.

Cheers,
JQ
CP2K| version string:                    CP2K version 2.3 (Development 
Version)
 CP2K| source code revision number:                                       
 12327

On Saturday, January 19, 2013 3:59:01 PM UTC+2, jgh wrote:
>
> Hi 
>
> the Wavlet Poisson solver uses internaly the FFTSG library. 
> This is hard coded and cannot be changed. You can still use 
> FFTW3 for all the other parts of the code. 
> There are some technical issues with this that affect performance, 
> but there should be no accuracy problem. 
>
> best regards 
>
> Juerg Hutter 
>   
>
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Physical Chemistry Institute   FAX   : ++41 44 635 6838 
> University of Zurich               E-mail:  hut... at pci.uzh.ch<javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zurich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: ----- 
> To: cp... at googlegroups.com <javascript:> 
> From: JingQiang 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 01/19/2013 08:49AM 
> Subject: [CP2K:4255] Poisson Solver's requirement for FFTSG library 
>
> Dear cp2k developers, 
>
> I am wondering why does wavelet based Poisson solver requires the usage of 
> FFTSG library for calculations? How does it affect the accuracy of our 
> results if FFTW3 library is used instead? 
>
> If this imposes a serious issue, can I suggest that the program shall not 
> proceed calculation once the FFTSG library is not used? Thank you. 
>
> Cheers, 
> JQ 
> PhD student, Tampere University of Technology.   
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