Ubuntu下安装snap包
我想在Ubuntu上用Mathpix Snipping Tool,官网上提示在Ubuntu中用以下命令安装.
sudo snap install mathpix-snipping-tool
但是一直卡在如下命令.
Download snap "core" (6673) from channel "stable"
于是去这个第三方平台下了mathpix-snipping-tool的.snap文件,想直接安装.snap文件.又报错.
snap install mathpix-snipping-tool.snap
error: cannot find signatures with metadata for snap "mathpix-snipping-tool.snap"
在这个论坛中,说是要
snap ack snipping-tool.assert
但是我在第三方平台中只能下.snap包,没有.assert文件.
If you don’t care about the assertion, you can run
snap install --dangerous, but then you won’t receive updates.
但是可以用 --dangerous参数.不管更新.
snap install --dangerous mathpix-snipping-tool.snap
半小时后,终于安装好了(泪).
常用命令
snap changes查看正在进行的changesudo snap abort ID杀死某个进程
效果
我一般在Ubuntu下写代码,所以想在Ubuntu下写笔记,同时用公式来解释代码非常直观.这是我在Ubuntu下安装Mathpix Snipping Tool的初衷.下面的公式就是用 ctr+alt+M组合键得到的公式.
R i = ( cos ( θ i ) − sin ( θ i ) sin ( θ i ) cos ( θ i ) ) \mathbf{R}_{i}=\left( \begin{array}{cc}{\cos \left(\theta_{i}\right)} & {-\sin \left(\theta_{i}\right)} \\ {\sin \left(\theta_{i}\right)} & {\cos \left(\theta_{i}\right)}\end{array}\right) Ri=(cos(θi)sin(θi)−sin(θi)cos(θi))
A i j = ∂ e i j ( x ) ∂ x i = ( − R i j ⊤ R i ⊤ R i j ⊤ ∂ R i ⊤ ∂ θ i ( t j − t i ) 0 ⊤ − 1 ) \mathbf{A}_{i j}=\frac{\partial \mathbf{e}_{i j}(\mathbf{x})}{\partial \mathbf{x}_{i}}=\left( \begin{array}{cc}{-\mathbf{R}_{i j}^{\top} \mathbf{R}_{i}^{\top}} & {\mathbf{R}_{i j}^{\top} \frac{\partial \mathbf{R}_{i}^{\top}}{\partial \theta_{i}}\left(\mathbf{t}_{j}-\mathbf{t}_{i}\right)} \\ {\mathbf{0}^{\top}} & {-1}\end{array}\right) Aij=∂xi∂eij(x)=(−Rij⊤Ri⊤0⊤Rij⊤∂θi∂Ri⊤(tj−ti)−1)
对应代码
Eigen::Matrix2d Rij_inv = (Zij.topLeftCorner(2,2)).transpose();
Eigen::Matrix2d Ri_inv = (Xi.topLeftCorner(2,2)).transpose();
Eigen::Matrix2d JR_theta;
JR_theta << -Xi(1,0), Xi(0,0),
-Xi(0,0), -Xi(1,0);
Ai.setZero();
Ai.topLeftCorner(2,2) = -Rij_inv * Ri_inv;
Ai.topRightCorner(2,1) = Rij_inv * JR_theta * (Xj.topRightCorner(2,1) - Xi.topRightCorner(2,1));
Ai(2,2) = -1;
Bi.setZero();
Bi.topLeftCorner(2,2) = Rij_inv * Ri_inv;
Bi(2,2) = 1;
参考
- snap教程https://itsfoss.com/use-snap-packages-ubuntu-16-04/