is there a log base 2 function?

This is a discussion on is there a log base 2 function? within the C Programming forums, part of the General Programming Boards category; I see a log and log10,in math.h, but how do I log base 2 ?...

  1. #1
    Temporal Apparition qubit67's Avatar
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    is there a log base 2 function?

    I see a log and log10,in math.h, but how do I log base 2 ?

  2. #2
    C++ Witch laserlight's Avatar
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    I believe you can use mathematics, i.e., the change of base formula.

    log_b(a) = log_c(a) / log_c(b)
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    Lean Mean Coding Machine KONI's Avatar
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    You can easily calculate a log in base x by doing:

    log (base x) (y) = log (y) / log (x)

    edit: damn ... too slow ...

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    Temporal Apparition qubit67's Avatar
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    thanks, i thought there was a work around

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