Differential equations are fundamental tools in physics: they are used to describe phenomena ranging from fluid dynamics to general relativity. But when these equations become stiff (i.e. they involve ...

It's a short week for the San Francisco 49ers after their first loss. With so many issues going into Thursday's game against the Rams, we had questions for the Chronicle's NFL coverage team.

If you use Excel 40 hours a week (and those are the weeks you are on vacation), welcome to the MrExcel channel. Home to 2,400 free Excel tutorials. Bill "MrExcel" Jelen is the author of 67 books about ...

Microsoft added some very useful features to Excel in September 2025, but many of them are exclusive to customers belonging ...