Really dumb question: why do we use e_i for unit vectors?

1. Mar 28, 2008

Peeter

Anybody know the history of why something like $$\mathbf{e}_i$$ is conventionally used for unit vectors (as opposed to u for Unit which is less common).

I assume this originates from another language? If so I'm curious what language and what word.

2. Mar 28, 2008

D H

Staff Emeritus
German, I suspect - ein.

3. Mar 28, 2008

Peeter

Ah. One (unit). Thanks!

4. Mar 28, 2008

I'd always been told it was short for "element."

5. Mar 28, 2008

HallsofIvy

Never believe what a math teacher tells you!

6. Mar 28, 2008

Pere Callahan

I agree, "e" for "Einheitsvektor" meaning unit vector.

Might also be derived from Euclidean though..who knows for sure..

7. Mar 28, 2008

sutupidmath

How come?

8. Mar 28, 2008

D H

Staff Emeritus
He's a math teacher trying to revive Epimenides paradox. Follow his advice: Don't believe anything he says.

9. Mar 28, 2008

sutupidmath

I am assuming he is implying with this, that we, students, must check everything out on our own, no matter who tells us that sth is true or not. We have to verify everything on our own, right, is this what halls is saying, right?

Ok, i am gonna check the meaning of that paradox on wiki.

Last edited: Mar 28, 2008
10. Mar 30, 2008

transgalactic

11. Mar 30, 2008

sutupidmath

12. Mar 30, 2008

transgalactic

aaahhh i know that from the "SAT" exam

those logic questions took a decade from my life

Last edited: Mar 30, 2008
13. Mar 31, 2008

LukeD

I actually found this discussion to be fairly informative. I never think that asking for historical reasons for notation is a stupid question.

14. Mar 31, 2008

Peeter

I should have labelled the post "non-technical question: ..." ;)

15. Apr 2, 2008

mathwonk

16. Apr 5, 2008

LukeD

Would there be something wrong with that?

17. Apr 5, 2008

HallsofIvy

Epimedes' paradox was to say that "All Cretan's are liars". Of course, Epimedes was himself a Cretan. There is, in fact, a place in the Bible (New Testament. I've forgotten exactly where but may be in Paul's epistle to the Corinthians) in which we are warned to beware of Cretans- "they say of themselves that they are liars"!