logarithm of base other than e,10 and 2

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shahid khan
shahid khan el 29 de Jul. de 2012
Comentada: Walter Roberson el 4 de Nov. de 2022
how do i find logarithms having base other than e, 10 and 2.

Respuesta aceptada

James Tursa
James Tursa el 29 de Jul. de 2012
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 comentario
Stephen23
Stephen23 el 18 de Abr. de 2020
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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Más respuestas (4)

Tsegts
Tsegts el 4 de Nov. de 2022
how to write that base 3 log

Chris Lucero
Chris Lucero el 18 de Abr. de 2020
Editada: Walter Roberson el 18 de Abr. de 2020
y = logb(magic(3),[1 2 3; 4 5 6; 7 8 9]);

Walter Roberson
Walter Roberson el 18 de Abr. de 2020
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 el 26 de Feb. de 2022
how do we convert from base 9 to base 12 in matlab
can you give me an example on it
  1 comentario
Walter Roberson
Walter Roberson el 26 de Feb. de 2022
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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