Function forward_hessian_nograd_sparse

pub fn forward_hessian_nograd_sparse<F>(
    f: &'_ dyn Fn(&Vec<F>) -> Result<F, Error>,
) -> impl Fn(&Vec<F>, Vec<[usize; 2]>) -> Result<Vec<Vec<F>>, Error> + '_
where
    F: Float + FromPrimitive + AddAssign,