base of a logarithmic function

639me's picture

does anyone know how to change the base of a log function using math expression? i'm having the same challenge in grapher.app, when trying to visualize a function.

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djfil's picture
Re: base of a logarithmic function

Logarithm of X on base B equals logarithm of X on base C divided by logarithm of B on base C Is this helpful?

cybero's picture
Re: base of a logarithmic function

Log y z = ( Log x z ) / ( Log x y )

Getting , say Log 12 of 16.

Gives you a variable based logarithm.

See attached JavaScript QC - thanks to Brian Risk for this nifty piece of scripting which I ported to the JS patch [original in comments area] , also contains an example Math Expression patch implimentation too.

Hope that helps .

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JS_ChangeBase.qtz5.19 KB