TestMath

$E=mc^{2}$

$A=\int _{0}^{1}{\frac {\ln {x}}{x}}\,\mathrm {d} x$

$z=\left\{{\begin{array}{ll}1&(x>0)\\0&(x<0)\end{array}}\right.$

$\left({\begin{matrix}K_{11}&K_{12}&K_{13}&\ldots &K_{1n}\\K_{21}&K_{22}&K_{23}&\ldots &K_{2n}\\K_{31}&K_{32}&K_{33}&\ldots &K_{3n}\\\vdots &\vdots &\vdots &\ddots &\vdots \\K_{n1}&K_{n2}&K_{n3}&\ldots &K_{nn}\end{matrix}}\right)\left({\begin{matrix}D_{1}\\D_{2}\\D_{3}\\\vdots \\D_{n}\end{matrix}}\right)=\left({\begin{matrix}F_{1}\\F_{2}\\F_{3}\\\vdots \\F_{n}\end{matrix}}\right)$