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Homework Help: Notation - f(x,a) vs f(x;a)

  1. Mar 10, 2010 #1
    1. The problem statement, all variables and given/known data

    Quick question...

    I have seen both being used : f(x,a) and f(x;a). What is the usual convention? Are both acceptable to denote functions of 2 variables (in this case f is a function of both x and a). Or are there vital differences between the two that I don't know about?

    Thanks! :)

    2. Relevant equations


    3. The attempt at a solution

  2. jcsd
  3. Mar 10, 2010 #2


    Staff: Mentor

    I don't recall ever seeing this notation -- f(x; a) -- being used.
  4. Mar 10, 2010 #3


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    Homework Helper

    notation like [tex] f(x;a) [/tex] is used in mathematical statistics when you want to show that a distribution depends on a parameter (real or vector-valued). for example, if you are talking about a normal distribution with some mean and standard deviation, writing
    [tex] \theta = (\mu, \sigma)[/tex] the density would be indicated [tex] f(x;\theta)[/tex]

    it indicates that the function depends on [tex] x [/tex] and involves a parameter [tex] \theta [/tex] (so, as we say in statistics, by varying [tex] \theta [/tex] we obtain not one but a family of normal distributions.
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