识别图片中的公式！免费的在线latex公式编辑器。支持导出svg、超大png、jpg、mathml、svgcode。可以打出任何公式，不只是数学！支持物理physics、化学mhchem、unicode等常用扩展宏包加载。即时渲染，基于mathjax实现。

since 1983, developing the free unix style operating system gnu, so that computer users can have the freedom to share and improve the software they use.

interactive open source numerical library of c/c++ functions for engineering, finance, maths, science and statistics. with online calculators for numerical components and excel add-ins.

github is where over 100 million developers shape the future of software, together. contribute to the open source community, manage your git repositories, review code like a pro, track bugs and features, power your ci/cd and devops workflows, and secure code before you commit it.

oi wiki 是一个编程竞赛知识整合站点，提供有趣又实用的编程竞赛知识以及其他有帮助的内容，帮助广大编程竞赛爱好者更快更深入地学习编程竞赛

stack overflow is the largest, most trusted online community for developers to learn, share​ ​their programming ​knowledge, and build their careers.