# \[Solved\] FFT issue in Gromacs 2023.2 Cuda Compilation/Configuration

**URL:** <https://gromacs.bioexcel.eu/t/solved-fft-issue-in-gromacs-2023-2-cuda-compilation-configuration/6843>\
**Category:** User discussions\
**Tags:** installation-error\
**Created:** [July 15, 2023, 11:21am UTC](https://gromacs.bioexcel.eu/t/solved-fft-issue-in-gromacs-2023-2-cuda-compilation-configuration/6843 "2023-07-15T11:21:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![organicchemistry\_01](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@organicchemistry\_01](https://gromacs.bioexcel.eu/u/organicchemistry_01)\
**Post date:** [July 15, 2023, 11:21am UTC](https://gromacs.bioexcel.eu/t/solved-fft-issue-in-gromacs-2023-2-cuda-compilation-configuration/6843/1 "2023-07-15T11:21:29Z")

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GROMACS version: 2023.2  
GROMACS modification: No

I am encountering an issue with compiling/building gromacs with cuda. cuFFT was properly detected however, the configuration encounters an error on -DGMX\_FFT\_LIBRARY, it was looking for the following:

fftw3, mlk or fftpack build in

Since it detected cuFFT, why does it want to build a cpu fftw?

If the intention of -DGMX\_FFT\_LIBRARY is a fall back it should be named something else like

-DGMX\_CPU\_FFT\_LIBRARY

:)

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**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\
**Post date:** [July 16, 2023, 12:01am UTC](https://gromacs.bioexcel.eu/t/solved-fft-issue-in-gromacs-2023-2-cuda-compilation-configuration/6843/2 "2023-07-16T00:01:04Z")

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Hi!

GROMACS always assumes that a valid CPU-only codepath is available, so it always needs a CPU FFT library. The CMake flag name is historic (pre-GPU). Our error reporting and documentation can perhaps be improved to make it less ambiguous.

If you are positive you are not ever running PME on CPU, you can choose `fftpack`; it does not have a stellar performance, but is very lightweight and is included with GROMACS. A more typical choice would be FFTW, with `-DGMX_BUILD_OWN_FFTW=ON` to build the bundled FFTW3 version since you presumably don’t have it installed system-wide. Neither of the two options require any external dependencies.