FFTBufferBase
Buffer for spectral executioners
FFTBufferBase is an ElementUserObject that holds information on domain variables for FFT solves. Buffers receive their initial value from Moose variables. Domain size, corner coordinates, dimensions, and k vector components can be accessed through methods such as getBoxSize, getMinCorner, dim and kTable, respectively. kTable provides a useful factor to perform computations in the reciprocal space. This is used, for example, in SpectralExecutionerBase to obtain spatial derivatives. FFTBufferBase holds pointers to the start of the buffer data, which has real and complex counterparts. Real space and reciprocal space data are member variables in the form of templated FFTData.
Real space data can be accessed by location, i.e. Point, through parenthesis operator methods. forwardRaw and backwardRaw are pure virtual methods which must be implemented in derived classes. FFTWBufferBase is an example of such classes, where direct and inverse discrete Fourier transforms are done via the external library FFTW (Fastest Fourier Transform in the West).