Function sprs::prod::mul_acc_mat_vec_csr

pub fn mul_acc_mat_vec_csr<N, I, Iptr, V>(
    mat: CsMatViewI<N, I, Iptr>, 
    in_vec: V, 
    res_vec: &mut [N]
) where
    N: Num + Copy,
    I: SpIndex,
    Iptr: SpIndex,
    V: DenseVector<N>, 

Multiply a sparse CSR matrix with a dense vector and accumulate the result into another dense vector