[ə¦sō·sē‚ād·əd ¦rād·dē‚ī əv kən′vər·jəns] (mathematics) For a power series in n variables, z1, . . , zn, any set of numbers, r1, . . , rn, such that the series converges when | zi | <>ri, i = 1, . . , n, and diverges when | zi | > ri, i = 1, . . , n.