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    [c] calculating logs using a variable base number?


    is there a math function in c to calculate a log using a variable base number?

    i can see log2 and log which is base 10, but what happens if you want other than base 10 or 2?


    edit: oh, i've just found out log is not base 10. it calculates the natural logarithm of the given number (which uses e right?). log10 is the base10 version of log that uses base 10
    Last edited by balance; April 25th, 2003 at 11:54 AM.
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    Code:
    blog(n)=clog(n) / clog(b)
    For any c>0 (not sure about the exact bounds for c). i.e. you can use either log10() or log() for the both :)
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    you confused me for a second there with your blogs'n'clogs (yes i did man blog and man clog :) ) , but i see what you mean now. got it. thanks.
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    they really should have taught you proper log functions in school.

    lets say i have 5^x and it equals 25 (5^2 = 25). we right that as
    log5 25, correct?
    to calculate that, use the log of the big number / log of small number. you put it into your calculator like this:
    log(25) / log(5)
    if your calculator works properly, it will tell you the answer is 2 :D

    just remember ----> big number over little number (big as in how big you write it, not the value)
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    woops sorry. i guess the page didn't update because i thought it didn't post lol.
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    i don't deny there's a few holes in my maths knowledge :)

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