Help identifying this Function

[markraz]

Does this look familiar to anyone? is there an official name for this thing?

 

[HallsofIvy]

Where did you see it? Was it on the internet? If so could you post a link? Was it in a book? If so, post the title. Context is everything!

 

[markraz]

Where did you see it? Was it on the internet? If so could you post a link? Was it in a book? If so, post the title. Context is everything!

Thanks ok sorry about that
it's in this video, right around 7:30 he starts explaining it.. He states what it is but I can't dicern exactly whay he says.

appreciate it