aspcol.kernelinterpolation.freq_to_time_domain_kernel_matrix

aspcol.kernelinterpolation.freq_to_time_domain_kernel_matrix(freq_kernel)

Turns a frequency domain kernel matrix into a time domain kernel matrix.

Could be made faster by using the RFFT directly, but this is a clear and easy to check implementation. Write unit tests against this function to implement a faster version.

Parameters:

freq_kernel (np.ndarray of shape (num_points1, num_points2, num_real_freqs, num_real_freqs)) – or (num_points1, num_points2, num_real_freqs) The frequency domain kernel matrix. If dimension is 3, the kernel is assumed to be diagonal.