1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What does this order symbol mean?

  1. Jan 3, 2009 #1


    User Avatar
    Gold Member

    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Jan 3, 2009 #2


    User Avatar
    Homework Helper

    It means "Order" as in "order of magnitude". [itex]\mathcal{O}(1)[/itex], when referring to some quantity, means that the order of magnitude of the quantity is on the order of the number 1 - it's larger than 0.1 and less than 10. Typically we take order of things as powers of some number.

    e.g. [itex]x \sim \mathcal{O}(\lambda^n)[/itex] means the variable x is of the same order of size as the parameter [itex]\lambda[/itex] to the nth power - it's between [itex]\lambda^{n-1}[/itex] and [itex]\lambda^{n+1}[/itex] in size.

    See http://en.wikipedia.org/wiki/Big_O_notation
  4. Jan 3, 2009 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    That is "on the order of". Its most general mathematics definition can be complicated but in this application saying "O(1)" really means "a few": less than 10 but more than 0.1. Saying that the lifetime of a proton is "O(1032) years" means that the lifetime of a proton is certainly greater than 1031 years but less than 1033 years.
    Last edited: Jan 5, 2009
  5. Jan 3, 2009 #4
  6. Jan 3, 2009 #5


    User Avatar
    Gold Member

    Thank you oh so very very much. I've noticed that there are letters that take a similar tex bitmap name; are they related?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: What does this order symbol mean?