摘要
本文证明了函数处处不可微的充分条件。对Weierstrass函数、Bush函数进行讨论，得到两个函数都处处不可微。
A sufficient condition of the function nondifferentiable everywhere is proved in this paper. Then the Weierstrass function and the Bush function are discussed ,that they are both nondifferentiable everywhere.
