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!

Identically zero

  1. May 25, 2014 #1

    joshmccraney

    User Avatar
    Gold Member

    hey pf!

    when would you use "identically zero" as opposed to simple "zero". example: f is identically zero on interval a to b. or, f is zero on interval a to b.

    why do we ever use identically? it seems superfluous...

    thanks!
     
  2. jcsd
  3. May 25, 2014 #2
    It's because the statement "##f## is zero on the interval ##[a,b]##", might be interpreted as there is a ##c\in [a,b]## such that ##f(c) = 0##. I know that the proper language should be that "##f## has a zero", rather than what I wrote. But writers want to be clear and write that it is identically zero to avoid misunderstandings.
     
  4. May 25, 2014 #3

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    'Identically' is sometimes used for emphasis.

    Of course, sin[itex]^{2}[/itex]θ + cos[itex]^{2}[/itex]θ is identically 1.
     
  5. May 26, 2014 #4

    joshmccraney

    User Avatar
    Gold Member

    thanks to you both!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook