Function gaussian_smooth_3d_masked_f64 

fn gaussian_smooth_3d_masked_f64(
    data: &[f64],
    mask: &[f64],
    nx: usize,
    ny: usize,
    nz: usize,
    sigmas: &[f64; 3],
) -> Vec<f64>

Gaussian smoothing with anisotropic sigma and mask