交错级数是形如 的级数（a_n ≥ 0）。 格兰迪级数是交错级数中的特殊情况。

关于交错级数，有一个审敛法：若各项非负的数列单调递减且趋于零，则级数 收敛。

In mathematics, an alternating series is an infinite series of the form

with a_n > 0 for all n. The signs of the general terms alternate between positive and negative. Like any series, an alternating series converges if and only if the associated sequence of partial sums converges.