A brief introduction to complex analysis

(underline{Def:})A func (U(subset mathbb{C}) stackrel{f}longrightarrow mathbb{C})is (complex) differentiable at a point (z_0 in intU)(int:内部)
If f is cpx diff at (z_0),we call the limit the (cpx) derivative of f at (z_0) and devote it by (f^{prime}(z_0))or (frac{df(z_0)}{dz})
if (U stackrel{f}longrightarrow mathbb{C})is (cpx)diff at every z