allow pyfftw even if MPI is not present

nifty/config/nifty_config.py

@@ -32,6 +32,7 @@ dependency_injector = keepers.DependencyInjector(
                                     'plotly'])
 
 dependency_injector.register('pyfftw', lambda z: hasattr(z, 'FFTW_MPI'))
+dependency_injector.register(('pyfftw','pyfftw_scalar'))
 
 # Initialize the variables
 variable_fft_module = keepers.Variable(

nifty/operators/fft_operator/transformations/rg_transforms.py

@@ -26,6 +26,7 @@ import nifty.nifty_utilities as utilities
 from keepers import Loggable
 
 pyfftw = gdi.get('pyfftw')
+pyfftw_scalar = gdi.get('pyfftw_scalar')
 
 
 class Transform(Loggable, object):
@@ -572,6 +573,10 @@ class NUMPYFFT(Transform):
             result : np.ndarray or distributed_data_object
                 Fourier-transformed pendant of the input field.
         """
+        # Enable caching for pyfftw_scalar.interfaces
+        if 'pyfftw_scalar' in gdi:
+            pyfftw_scalar.interfaces.cache.enable()
+
         # Check if the axes provided are valid given the shape
         if axes is not None and \
                 not all(axis in range(len(val.shape)) for axis in axes):
@@ -625,10 +630,16 @@ class NUMPYFFT(Transform):
             local_val = self._apply_mask(temp_val, mask, axes)
 
         # perform the transformation
-        if self.codomain.harmonic:
-            result_val = np.fft.fftn(local_val, axes=axes)
+        if 'pyfftw_scalar' in gdi:
+            if self.codomain.harmonic:
+                result_val = pyfftw_scalar.interfaces.numpy_fft.fftn(local_val, axes=axes)
+            else:
+                result_val = pyfftw_scalar.interfaces.numpy_fft.ifftn(local_val, axes=axes)
         else:
-            result_val = np.fft.ifftn(local_val, axes=axes)
+            if self.codomain.harmonic:
+                result_val = np.fft.fftn(local_val, axes=axes)
+            else:
+                result_val = np.fft.ifftn(local_val, axes=axes)
 
         # Apply domain centering mask
         if reduce(lambda x, y: x + y, self.domain.zerocenter):