Function add_row 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn add_row(
    mat: *mut Matrix<'_>,
    v: *mut f64,
    n: usize,
)

Adds a row to the Matrix.

Safety

1, mat should point to a valid Matrix object created by create_matrix.
2. v should point to a valid array of doubles of length at least n.
3. v should remains valid for the lifespan of mat.