fixes

README.md

@@ -64,11 +64,6 @@ NIFTy5 and its mandatory dependencies can be installed via:
     sudo apt-get install git python3 python3-pip python3-dev
     pip3 install --user git+https://gitlab.mpcdf.mpg.de/ift/NIFTy.git@NIFTy_5
 
-(Note: If you encounter problems related to `pyFFTW`, make sure that you are
-using a pip-installed `pyFFTW` package. Unfortunately, some distributions are
-shipping an incorrectly configured `pyFFTW` package, which does not cooperate
-with the installed `FFTW3` libraries.)
-
 Plotting support is added via:
 
     pip3 install --user matplotlib

docs/source/installation.rst

@@ -7,18 +7,29 @@ distributions, the "apt" lines will need slight changes.
 
 NIFTy5 and its mandatory dependencies can be installed via::
 
-    sudo apt-get install git libfftw3-dev python3 python3-pip python3-dev
+    sudo apt-get install git python3 python3-pip python3-dev
     pip3 install --user git+https://gitlab.mpcdf.mpg.de/ift/NIFTy.git@NIFTy_5
 
+Plotting support is added via::
+
+    pip3 install --user matplotlib
+
+FFTW support is added via:
+
+    sudo apt-get install libfftw3-dev
+    pip3 install --user pyfftw
+
+To actually use FFTW in your Nifty calculations, you need to call
+
+    nifty5.fft.enable_fftw()
+
+at the beginning of your code.
+
 (Note: If you encounter problems related to `pyFFTW`, make sure that you are
 using a pip-installed `pyFFTW` package. Unfortunately, some distributions are
 shipping an incorrectly configured `pyFFTW` package, which does not cooperate
 with the installed `FFTW3` libraries.)
 
-Plotting support is added via::
-
-    pip3 install --user matplotlib
-
 Support for spherical harmonic transforms is added via::
 
     pip3 install --user git+https://gitlab.mpcdf.mpg.de/ift/pyHealpix.git