1. Jan 29, 2015 #1

   22990atinesh

   

   I've a small confusion about formula
   ##\log^3 n = \log \log \log n##
   or ##\log^3 n = (\log n)^3 ##

    

   22990atinesh, Jan 29, 2015
2. 
   Phys.org - latest science and technology news stories on Phys.org

   • • Game over? Computer beats human champ in ancient Chinese game
   • • Simplifying solar cells with a new mix of materials
   • • Imaged 'jets' reveal cerium's post-shock inner strength
3. Jan 29, 2015 #2

   Doc Al

   

   Staff: Mentor

   That's the one you want.

    

   Doc Al, Jan 29, 2015
4. Jan 29, 2015 #3

   Mark44

   

   Insights Author

   Staff: Mentor

   In exactly the same way, cos²(x) does not mean cos(cos(x)), but rather it means cos(x) * cos(x) = (cos(x))². The exponent indicates repeated multiplication, not repeated function composition.

    

   Mark44, Jan 29, 2015
5. Jan 29, 2015 #4

   HallsofIvy

   

   Staff Emeritus

   Science Advisor

   It is not uncommon to put a an exponent in parentheses to indicate a repeated composition.
   That is, [itex](log(x))^{(3)}[/itex] or [itex]log^{(3)}(x)[/itex] is "log(log(log(x)))".
   
   Unfortunately, that is also often used to indicate the third derivative so you must be careful to state which!

    

   Last edited: Jan 30, 2015

   HallsofIvy, Jan 29, 2015
6. Jan 31, 2015 #5

   22990atinesh

   

   You mean ##\log^{(3)} n = (\log n)^{(3)} = \log (\log(\log n))##
   ##\log^3 n = (\log n)^3##

    

   22990atinesh, Jan 31, 2015
7. Jan 31, 2015 #6

   Mark44

   

   Insights Author

   Staff: Mentor

   The above is what HallsOfIvy said. I haven't seen it, myself, but I have seen f⁽³⁾, with parentheses around the exponent, to indicate the third derivative.
   

   This is what I said.

    

   Mark44, Jan 31, 2015
8. Jan 31, 2015 #7

   22990atinesh

   

   I know, I was just rechecking from you. :)

    

   22990atinesh, Jan 31, 2015

• Log in with Facebook
• Log in with Twitter

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in