Initialisation, match case

init_match.rs

match i {
        Init::Const(cst) => {
            // Optimize the case for which a single C++ code can be done.
            if cst == 0. {
                Tensor::f_zeros(dims, (Kind::Float, device))
            } else if (cst - 1.).abs() <= std::f64::EPSILON {
                Tensor::f_ones(dims, (Kind::Float, device))
            } else {
                Tensor::f_ones(dims, (Kind::Float, device)).map(|t| t * cst)
            }
        }