Fourier transform and 2nd derivative matrix corrections #232
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Description
This corrects two mathematical issues in the code:
core.td_to_fd
function no longer multiplies the DC and Nyquist frequency by two, since these frequencies would not have Hermitian symmetry and therefore should not by doubled when converting from a double-sided to a single-sided spectrumcore.derivative2_mat
, has been added to correctly enable acceleration calculations from position. With Remove sine component of 2-point wave #191, the final velocity term is (correctly) zero, so performingderivative_mat @ velocity
returns zero for the final acceleration term as well, though this should usually be nonzero. An explicit second derivative matrix allows for this term to be captured viaderivative2_mat @ position
instead of usingderivative_mat
twice on the position vector.Type of PR
Checklist for PR