# Meaning of | In Mathematical Equation **URL:** \ **Category:** Factual Questions\ **Created:** [May 27, 2004, 2:09pm UTC](https://boards.straightdope.com/t/meaning-of-in-mathematical-equation/247337 "2004-05-27T14:09:01Z")\ **Posts on this page:** 2\ **Page:** 2
**Author:** ![Go\_You\_Big\_Red\_Fire\_Engine](https://avatars.discourse-cdn.com/v4/letter/g/eada6e/32.png) [@Go\_You\_Big\_Red\_Fire\_Engine](https://boards.straightdope.com/u/Go_You_Big_Red_Fire_Engine)\ **Post date:** [May 28, 2004, 10:44am UTC](https://boards.straightdope.com/t/meaning-of-in-mathematical-equation/247337/21 "2004-05-28T10:44:02Z")
That is called a **schaefer** (sic) stroke. If I could find my text book, I could give you the proper spelling :rolleyes: Ah, found it. \*\*Scheffer \*\* stroke A quick summary of what everyone is saying… |x| absoloute value of x | can mean NAND or d|n = d divides n, ie. d|n = k, where k belongs to Z or it can simply mean “such that” ---
**Author:** ![crozell](https://avatars.discourse-cdn.com/v4/letter/c/3da27b/32.png) [@crozell](https://boards.straightdope.com/u/crozell)\ **Post date:** [May 28, 2004, 2:17pm UTC](https://boards.straightdope.com/t/meaning-of-in-mathematical-equation/247337/22 "2004-05-28T14:17:08Z")
> [@Jon the Geek](#): > > What does the | in a mathematical equation mean? For example, in this equation: > f(theta|u) \ f(u|theta)f(theta) > what do the |'s mean? > > I believe it’s something from linear algebra and/or statistics, but it isn’t ringing a bell from either. Granted, I took those classes about 10 years ago… Another vote for [Bayes’ Theorem](http://mathworld.wolfram.com/BayesTheorem.html) here. Yes, the | symbol can have many different meanings, but in this case I would say you are definately dealing with conditional probabilities in an expression of Bayes’ classic formula. [Previous page](https://boards.straightdope.com/t/meaning-of-in-mathematical-equation/247337.md?page=1)