fn resharp_kernel(n: (usize, usize, usize), r: [usize; 3]) -> Vec<f64>Expand description
resharp.m’s kernel (l. 43-45): the voxels of the rx×ry×rz ellipsoid
(X²/rx² + Y²/ry² + Z²/rz² ≤ 1, in voxels), normalised to sum 1, centred at index (0,0,0)
of an n grid for FFT use (Fortran order).