Navier-Stokes Equations:
$$ \rho {\frac {D{\vec {v}}}{Dt}}=\rho \left({\frac {\partial {\vec {v}}}{\partial t}}+({\vec {v}}\cdot \nabla ){\vec {v}}\right)=-\nabla p+\mu \Delta {\vec {v}}+(\lambda +\mu )\nabla (\nabla \cdot {\vec {v}})+{\vec {f}}$$
The Quadratic Formula:
$$x = {-b \pm \sqrt{b2-4ac} \over 2a}.$$
Cauchy's Integral Formula:
$$f(a) = \frac{1}{2\pi i} \oint\frac{f(z)}{z-a}dz$$
Standard Deviation: $\sigma = \sqrt{ \frac{1}{N} \sum_{i=1}N (x_i -\mu)2}$
@unagi 怎么看起来还有点眼熟??