logarithm of base other than e,10 and 2

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shahid khan
shahid khan 2012-7-29
评论： Walter Roberson 2022-11-4
how do i find logarithms having base other than e, 10 and 2.

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采纳的回答

James Tursa
James Tursa 2012-7-29
logB(X) = logA(X) / logA(B)
You can pick A to be one of the built in functions, like log or log2 or log10. E.g.,
log3(9) = log(9) / log(3) , or
log3(9) = log10(9) / log10(3) , etc.
  1 个评论
Stephen23
Stephen23 2020-4-18
Note that for many MATLAB versions log10 itself called log2 internally... so you might as well skip the intermediate log10 and just call log2 directly (it is probably more accurate as well).

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更多回答（4 个）

Tsegts
Tsegts 2022-11-4
how to write that base 3 log
Chris Lucero
Chris Lucero 2020-4-18
编辑：Walter Roberson 2020-4-18
y = logb(magic(3),[1 2 3; 4 5 6; 7 8 9]);
Walter Roberson
Walter Roberson 2020-4-18
if you really get desparate:
arrayfun(@(V) feval(symengine,'log', B, V), A)
and you might want to double() the result. Note that for this to work, B must be a positive real number, whereas in Jame's solution of log(A)/log(B) then B does not need to be positive and does not need to be real-valued.
lina al noaimi
lina al noaimi 2022-2-26
how do we convert from base 9 to base 12 in matlab
can you give me an example on it
  1 个评论
Walter Roberson
Walter Roberson 2022-2-26
If you mean numeric base, in the same sense that Hexadecimal representation is base 16 number system, then use base2dec and dec2base.
If you mean log base then log12(x) = log9(x).^(9/12)

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