Re: Request for Assistance on Logs/Anti-LOGS
[Prev][Next][Index][Thread]
Re: Request for Assistance on Logs/Anti-LOGS
> 1. with mode set to "Exact", 10^2.307 ENTER returns 100x10^(307/1000)
...because 10^(2.307)=10^(2 + .307)=10^2 * 10^.307 (law of exponents)
> 2. with mode set to "approximate" , 10^2.307 ENTER returns 202.768
...because log(202.768) ~= 2.307
> 3. with mode set to "auto" , 10^2.307 ENTER returns 202.768
...because the system sees the "." and decides to give approx result "for
our own good" (see 1!).
> 4. with mode set to "Exact", log 52 ENTER returns Ln(52)/Ln(10)
... because log(52)=y where 10^y=52 (def of log), whereupon (internally) the
system solves for y by taking Ln of both sides, getting
Ln(10^y)=Ln(52), to which it applies the "power property" of logs (moving
the exponent to left of ln), getting
y*Ln(10)=Ln(52), which it then divides to get
y=Ln(52)/Ln(10)
> 5. with mode set to "approximate" , log 52 ENTER returns 1.716
... because 10^1.716 ~= 52
> 6. with mode set to "auto" , log 52 ENTER returns Ln(52)/Ln(10)
...to encourage use of Ln, the 89/92 default log for symbolic operations.
> The software is not entirely consistent.
I'll bet it is!
>But, usually "exact" mode returns
> Ln(a)/Ln(10) for log(a), accurate but not helpful.
It's helpful if you're in exact mode for symbolic purposes.
>On the other hand if you
> set the mode to "approximate" then a numerical value is returned.
...as it is if you have ANY mode set and use the "green equals" (~=) key OR
include a decimal point in any number in the expression being evaluated.
> I don't know what changes may result from downloading version 2 of the
> software.
Hopefully NONE, but it might be useful to have a "default log" selector
option, for those who prefer base 10 log over the "natural" (base e) log of
calculus (Ln).
Dave Slomer
Greenhills, OH
davidslomer@geocities.com
http://www.geocities.com/CapeCanaveral/Lab/8692/
******************************************************************
* To UNSUBSCRIBE, send an email TO: listserv@lists.ppp.ti.com
* with a message (not the subject) that reads SIGNOFF CALC-TI
*
* Archives at http://peach.ease.lsoft.com/archives/calc-ti.html
******************************************************************
References: