‎对于线性方程组<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/aaee12f2064948169b33d28fe723ef96.png?x-oss-process=image/sharpen,200"/><img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/eb16a008baed486cbd00f592d25cb158.png?x-oss-process=image/sharpen,200"/>均不为零，则Jacobi迭代法收敛的充分必要条件为_______