Abstract
In a former paper, Inoue introduced an interpolation based on a scheme in the charge simulation method, but he did not mention the problem whether the coefficient matrix derived there is regular or not. We will first point out unnaturalness of his scheme and introduce another interpolation based on so-called Murota's invariant scheme, which is a slightly modified version of Inoue's scheme. Then we will guarantee that the coefficient matrix for our scheme is always regular.
