def pad_position_w(self, i):
        """
        Determines the position of the ith pad in the width direction.
        Assumes equally spaced pads.

        :param i: ith number of pad in width direction (0-indexed)
        :return:
        """
        if i >= self.n_pads_w:
            raise ModelError("pad index out-of-bounds")
        return (self.width - self.pad_width) / (self.n_pads_w - 1) * i + self.pad_width / 2