数学公式

数学公式：

公式在html中

$h(\theta)=\sum_{j=0}^n \theta_jx_j$ (线性模型)

$J(\theta)=\frac1{2m}\sum_{i=0}(y^i-h_\theta(x^i))^2$ （均方误差orcostfunction）

$\iiiint_{F}^{U} \, dx\,dy\,dz\,dt$

$\begin{matrix} 1 & x & x^2 \\ 1 & y & y^2 \\ 1 & z & z^2 \\ \end{matrix}$

$\left\{ \begin{array}{c} a_1x+b_1y+c_1z=d_1 \\ a_2x+b_2y+c_2z=d_2 \\ a_3x+b_3y+c_3z=d_3 \end{array} \right.$

$X=\left( \begin{matrix} x_{11} & x_{12} & \cdots & x_{1d}\\ x_{21} & x_{22} & \cdots & x_{2d}\\ \vdots & \vdots & \ddots & \vdots\\ x_{m1} & x_{m2} & \cdots & x_{md}\\ \end{matrix} \right) =\left( \begin{matrix} x_1^T \\ x_2^T \\ \vdots\\ x_m^T \\ \end{matrix} \right)$

$\begin{align} \frac{\partial J(\theta)}{\partial\theta_j} & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(y^i-h_\theta(x^i)) \\ & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i)) \frac{\partial}{\partial\theta_j}(\sum_{j=0}^n\theta_jx_j^i-y^i) \\ & = -\frac1m\sum_{i=0}^m(y^i-h_\theta(x^i))x^i_j \end{align}$

$\begin{align} \because\begin{cases} \acute{a}x^2+bx^2+c\gtrless0\gtrless\grave{a}x^2+bx^2+c\\ \acute{a}>0>\grave{a} \end{cases}\\ \therefore\frac{-b\pm\sqrt{b^2-4\acute{a}c}}{2\acute{a}}{}_\lessgtr^\gtrless x_\lessgtr^\gtrless\frac{-b\pm\sqrt{b^2-4\grave{a}c}}{2\grave{a}} \end{align}$

参考文档：https://www.cnblogs.com/Sinte-Beuve/p/6160905.html

资料库：https://blog.csdn.net/u013346007/article/details/54138690

posted @ 2018-07-06 10:40 coding_the_life 阅读(107) 评论(0) 收藏举报

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数学公式

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