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A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.

Posts

GraphHopper paths are edges, not nodes

3 minute read

Published:

GraphHopper makes a deliberate design choice: paths are represented by edges, not nodes. This matters for correctness (turn restrictions/costs), fidelity (multiple parallel edges between the same nodes), and efficiency (edge properties drive routing).

GPT Chats

6 minute read

Published:

Some chats from ChatGPT

argmax to multinomial

2 minute read

Published:

Why use a multinomial function to get the next word prediction in a GPT (generative) model rather than outputting the id with the largest probability?

解决Ubuntu中文字体缺失,中文文档丑

less than 1 minute read

Published:

Ubuntu下使用WPS, LibreOffice编辑文档、演示稿时,发现Ubuntu自带的(免费)字体丑。同样的文档在Windows,MAC下看着没问题,在Ubuntu下排版都乱了(字体宽度不一样)。将Windows的中文字体拷过来就好了。

Fundamental Theorem of Linear Programming

1 minute read

Published:

Fundamental Theorem of Linear Programming Given a linear program in standard form where A is an m × n matrix of rank m,

  1. (T1) if there is a feasible solution, there is a basic feasible solution;
  2. (T2) if there is an optimal feasible solution, there is an optimal basic feasible solution.

Optimization Problems

2 minute read

Published:

Problem summary of High-Dimensional Data Analysis with Low-Dimensional Models - John Wright, Yi Ma

L1 optimization by projected subgradient [python]

1 minute read

Published:

Python implementation of Algorithm L1-Minimization by Projected Subgradient from High-Dimensional Data Analysis with Low-Dimensional Models - John Wright, Yi Ma, Page 63

Projection onto an Affine Subspace

1 minute read

Published:

Let \(A\) be a matrix with size \(m \times n\). We want to project point z onto a plane \(\begin{align} \arg \min_{x} \lVert z-x \rVert_2 \\ \text{s.t. } Ax = y \end{align}\)

Subset Selection [python]

1 minute read

Published:

Python implementation of Algorithm L0-Minimization by Exhaustive Search from High-Dimensional Data Analysis with Low-Dimensional Models - John Wright, Yi Ma, Page 48

ros2/arm免依赖交叉编译教程

1 minute read

Published:

使用qemu运行arm docker模拟器,在模拟器中使用apt安装依赖后,将docker容器文件系统导出,作为cmake的sysroot,避免编译依赖。本文以ROS2为例,但方法并不限于ROS2

vietnam

less than 1 minute read

Published:

Nhatrang