# Installing GROMACS with first manually installing fftw3 library

**URL:** <https://gromacs.bioexcel.eu/t/installing-gromacs-with-first-manually-installing-fftw3-library/3283>\
**Category:** User discussions\
**Tags:** installation-error\
**Created:** [December 10, 2021, 5:39pm UTC](https://gromacs.bioexcel.eu/t/installing-gromacs-with-first-manually-installing-fftw3-library/3283 "2021-12-10T17:39:52Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yogeshb](https://avatars.discourse-cdn.com/v4/letter/y/bc79bd/32.png) [@Yogeshb](https://gromacs.bioexcel.eu/u/Yogeshb)\
**Post date:** [December 10, 2021, 5:39pm UTC](https://gromacs.bioexcel.eu/t/installing-gromacs-with-first-manually-installing-fftw3-library/3283/1 "2021-12-10T17:39:52Z")

</div>

GROMACS version: 2021.4  
GROMACS modification: No  
For some reason, I cannot install gromacs with options -  
cmake … -DGMX\_BUILD\_OWN\_FFTW=ON -DREGRESSIONTEST\_DOWNLOAD=ON

unable to download automatically due to firewall restrictions. I want to install gromacs after first manually installing fftw3 library.  
I have fftw-3.3.8.tar.gz file.  
I tried below install for fftw3.  
**./configure --enable-float --enable-sse2 --enable-avx --enable-avx2**  
**make**  
**make install**

then I am trying to give location of fftw3 install, mine is at /usr/local/bin/

Gromacs may be looking for libfftw3f.so file, as they have given example of setting path as -DFFTWF\_LIBRARY=’/path/to/libfftw3f.so’

But my path (/usr/local/bin/) has only one file - fftwf-wisdom  
gromacs doesn’t accept this file.

Can anyone give sequence of command for gromacs installation using fftw3 manual install on PC.

---

<div class="post-metadata">

**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [December 11, 2021, 12:55pm UTC](https://gromacs.bioexcel.eu/t/installing-gromacs-with-first-manually-installing-fftw3-library/3283/2 "2021-12-11T12:55:48Z")

</div>

> [@Yogeshb](#):
>
> then I am trying to give location of fftw3 install, mine is at /usr/local/bin/

This would be rather odd; there are no relevant binaries that you need from FFTW. You need the libraries and headers. Do you mean you installed an “fftw” subdirectory in /usr/local/bin, or what?

I would strongly recommend a clean approach of installing FFTW with `--prefix=/usr/local/fftw` (or something similar) because then you can very simply add `-DCMAKE_PREFIX_PATH=/usr/local/fftw` to find everything that is needed for the installation, as cmake will automatically find the include and lib subdirectories.

---

<div class="post-metadata">

**Author:** ![Yogeshb](https://avatars.discourse-cdn.com/v4/letter/y/bc79bd/32.png) [@Yogeshb](https://gromacs.bioexcel.eu/u/Yogeshb)\
**Post date:** [December 11, 2021, 1:29pm UTC](https://gromacs.bioexcel.eu/t/installing-gromacs-with-first-manually-installing-fftw3-library/3283/3 "2021-12-11T13:29:03Z")

</div>

Thank you Justin. I will try clean install.