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What does [x] means in mathematics ?

  1. Mar 16, 2006 #1
    what does [x] means in mathematics ?

    i have found [x]= "the greatest integer <=x "

    is this true ?

    then, what will be the answer of of .....

    i am trying to answer, please correct me


    are these correct ?
  2. jcsd
  3. Mar 16, 2006 #2


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    [] meaning greatest integer is a common use of the [], but it can vary.You should check whatever book your problems are from, they should define what they mean by the notation.

    If it is the greatest integer function, then "[-1.5]=-1" isn't correct. You want the greatest integer less than or equal to -1.5, so it can't be -1 as -1.5<-1.
  4. Mar 16, 2006 #3

    jim mcnamara

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    So, in what way is the defintion for [tex][ x ][/tex] you've given different from [tex]\lfloor x \rfloor [/tex] ? - also given to be the symbol for the floor function, which matches the definition you gave.

    None, AFAIK, just a "who's the author" thing.

    IMO, it's just a bad nomen confusum problem. I've also seen it used in characteristic functions. Somebody ought to pick one use, and pitch the rest.... :) and penalize deviating authors 10 points for misuse. :)
  5. Mar 16, 2006 #4

    matt grime

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    Rubbish, Jim: there are far too few symbols possible and far too meanings that need to be conveyed. Context makes it clear what is going on.
  6. Mar 16, 2006 #5


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    Uniqe and fossilized use of symbols is counter-productive of developing flexibility of the mind. It is the definition AT HAND that matters, and if the chosen notation is convenient for its purpose.
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