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When VASP 5 was released, the performance was mostly slower than our make of VASP 4.6. I wrote it off as an optimization issue, and went on in my life. Then, in VASP 5.2, with the release notes, I realized that the it was all due to slower FFT, and is now fixed. Is there any way for me, as a user, to tell if the VASP make that I am using is built with the faster FFTW?

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There are a few possibilities:

  • Ask whoever built it. :)
  • Run strings vasp | grep -i fft and see if there's evidence of the version buried in the executable.
  • Run ldd vasp and look for a dynamically linked fft library. This last option is unlikely to produce results because you're more likely to have a static FFTW library (if I recall the build process for FFTW correctly).
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    $\begingroup$ To expand on this answer, you could also try: nm vasp | grep fftw to take a look for some of the FFTW symbols assuming that the executable hasn't been stripped. $\endgroup$ – Aron Ahmadia Nov 30 '11 at 13:13
  • $\begingroup$ That's a great point, Aron, though I recommend grep -i in this context. $\endgroup$ – Bill Barth Dec 2 '11 at 15:04

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