Function apply_laplacian_inplace 

fn apply_laplacian_inplace(
    output: &mut [f32],
    input: &[f32],
    mask: &[u8],
    nx: usize,
    ny: usize,
    nz: usize,
    vsx: f32,
    vsy: f32,
    vsz: f32,
)

Apply Laplacian with mask