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Developers Guide¶

Search and replace patterns¶

Correct alignment of pfft.h header

%s/^\(    [^ ]\+[^\\]*\)  \\/  \1\\/g

Expand most macros of pfft.h to generate the function reference of this manual:

sed -e 's/ *\\$//g' -e 's/PFFT_EXTERN //g' \
    -e 's/PX(\([^)]*\))/pfft_\1/g' -e 's/ INT/ ptrdiff_t/g' \
    -e 's/ R/ double/g' -e 's/ C/ pfft_complex/g' \
    -e 's/^  //g' pfft.h > pfft.h.expanded

ToDo¶

PFFT_FORWARD is defined as FFTW_FORWARD
FFTW_FORWARD is defined as \(-1\)
PFFT allows to chose between FFTW_FORWARD and FFTW_BACKWARD, which is not implemented by FFTW.
Matlab uses the same sign convention, i.e., \(-1\) for fft and \(+1\) for ifftn

Measuring parallel run times¶

Use MPI_Barrier in front of every call to pfft_ function to avoid unbalanced run times.