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Homework Help: Dex error system.

  1. Mar 21, 2012 #1
    1. The problem statement, all variables and given/known data

    I've been reading various journal articles about black hole masses. The values given there are given by X +/- Y dex. I cannot find any literature on "dex" nor do the articles go into detail as it is evidently a basic concept that I've just never come across.

    Could someone enlighten me?
  2. jcsd
  3. Mar 21, 2012 #2


    Staff: Mentor

    from this website I got the definition of dex as:

    a logarithmic unit being used in astronomy. Originally, dex was a convenient function defined by dex (x) = 10x. But the notation is now being used after the exponent in expressions such as -.043 dex, meaning 10-.043. Thus 1 dex equals a factor of 10, making the dex identical to the bel. The name "dex" is a contraction of "decimal exponent."

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