Einstein summation notation (was: question of style)

Erik Max Francis max at alcyone.com
Thu Jul 16 21:18:56 EDT 2009

Albert van der Horst wrote:
> Einstein introduced the summation convention for indices that
> are used twice. Leaving out summation signs is absolutely hideous,
> but it has saved generations of physicists of loosing track (and
> their minds.)

There is a joke among mathematicians that if Einstein hadn't been 
remembered for a couple of other fairly contributions things in physics 
:-), he would have been remembered in mathematics for that convention, 
since it has saved everyone -- mathematicians included -- a lot of time 
and anguish.  When using tensor calculus, there's even very easy ways to 
verify you have a valid tensor equation using it.

Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
  San Jose, CA, USA && 37 18 N 121 57 W && AIM/Y!M/Skype erikmaxfrancis
   If the sky should fall, hold up your hands.
    -- (a Spanish proverb)

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