log base 10

log base 10

asked 2011-12-01 12:46:54 +0100

Jason
77 ●4 ●6 ●11

Is there a built-in way to use a log with base other than e? The log documentation doesn't show any example (I thought log(10,x) was what I wanted for a while but it's actually different than what one might expect).

answered 2011-12-01 13:07:22 +0100

kcrisman
12242 ●42 ●136 ●255

This is in log?:

   EXAMPLES:

      sage: log(e^2)
      2
      sage: log(1024, 2); RDF(log(1024, 2))
      10
      10.0

So log(x,10) should be what you're looking for...

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Thanks, I wasn't aware that log_b(x) was equivalent to log(x)/log(b). Might be good to add that to the docs. (I got hung up because I saw log(10)/log(2) in the log? documentation and assumed it meant that log(x,y) was something that didn't help me, because it didn't say "To use the log in base b, do this")

Jason ( 2011-12-01 13:23:51 +0100 )edit

Well, the very first line of `log?` is "Return the logarithm of x to the given base." See http://www.sagemath.org/doc/reference/sage/functions/log.html#sage.functions.log.log. But if you think we should be a little more explicit, let us know and we could open a ticket...

kcrisman ( 2011-12-01 15:53:05 +0100 )edit

If you could make this change it would be great: "EXAMPLES: sage: log(e^2)" : To something like: EXAMPLES: To change the base of the logarithm, add a second parameter. sage: log(1000,10): 3 Small change but helpful!

Jason ( 2011-12-01 16:16:40 +0100 )edit

This is now http://trac.sagemath.org/sage_trac/ticket/12113.

kcrisman ( 2011-12-03 10:46:20 +0100 )edit

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