def _calculate_relative_offset(self, name, access_dimensions):
        """
        Return the offset from the iteration center in number of elements.

        The order of indices used in access is preserved.
        """
        # TODO to be replaced with compile_global_offsets
        offset = 0
        base_dims = self.variables[name][1]

        for dim, offset_info in enumerate(access_dimensions):
            offset_type, idx_name, dim_offset = offset_info
            assert offset_type == 'rel', 'Only relative access to arrays is supported at the moment'

            if offset_type == 'rel':
                offset += self.subs_consts(
                    dim_offset*reduce(operator.mul, base_dims[dim+1:], sympy.Integer(1)))
            else:
                # should not happen
                pass

        return offset
Return the offset from the iteration center in number of elements.

        The order of indices used in access is preserved.