NFFT precomputation strategy.
This method implements a linear interpolation from a lookup table.
This method uses a medium amount of memory to store d*(2*m+1)*M real numbers and requires at most
2(2m + 1)d extra multiplications for each node.
This is the default option.
Is the fastest method but requires a large amount of memory as it requires to store (2*m+1)^d*M
real numbers. No extra operations are needed during matrix vector multiplication.
math/nfft.F90 : 148
call parse_variable(namespace, 'NFFTPrecompute', NFFT_PRE_PSI, nfft%precompute)
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