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MaureenOD
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Converting logarithms to decimals

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HP Prime Graphing Calculator

How can I get my HP Prime Graphing calculator to answer log to base 2 of 3 with a decimal instead of LN(3)/LN(2)?

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Joe_Horn
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There are several ways, depending on whether you're in Home or CAS.

 

In Home view, the most efficient way is to use the LOG key to type LOG(3,2).  This returns the decimal value of logb(3,2).

Another method is to type logb(3,2) Enter, then EVAL(Ans) Enter. EVAL is Shift comma.

 

In CAS, any of these methods work:

-- Type LOG(3,2.) noticing that LOG is spelled in uppercase letters and the 2 has a decimal point after it.

-- Type logb(3,2.) with a decimal point.

-- Type logb(3,2) Enter, then press the [a b/c] key to approximate it.

 

Since CAS is intended for exact symbolic math, and Home is intended for floating-point number crunching, I'd suggest using the first option above, namely LOG(3,2) in Home.

 

Hope that helps!  Disclaimer: I don't work for HP. I'm just another happy HP calculator user.

-Joe-
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MaureenOD
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Unfortunately EVAL(Ans) just gives me  the same ratio of two natural logs.

 

LOG(3,2.)  gives me [LN(3) LN(2)]

 

Inputting the function is not the issue.  I can enter logs to whatever base I like from the menu on the key with Units and C.  What I need is the answer in the form of a decimal number instead of an exact value based on natural logs.

 

I tried the "a b/c" button earlier and it had no effect. Since then I have been messing around in the settings menus and now it works.  

 

Thanks for your advice.

 

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