ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: zada on November 09, 2008, 10:09:25 pm

Title: ln or loge?
Post by: zada on November 09, 2008, 10:09:25 pm: Am i allowed to write ln instead of log_e on exams? I've gotten into the habit of writing ln (it's shorter!).
Title: Re: ln or loge?
Post by: chid on November 09, 2008, 10:10:45 pm: Shouldn't make a i difference but just to be sure I would stick with loge it's only 2 extra figures! ;)
Title: Re: ln or loge?
Post by: shinny on November 09, 2008, 10:13:23 pm: Don't do it. It's just calculator notation, not formal maths notation. It's the same as not being allowed to write 10^3 or whatever.
Title: Re: ln or loge?
Post by: fredrick on November 09, 2008, 10:14:04 pm: yeh they dont allow answers like 3E-5, so i wouldnt risk it
Title: Re: ln or loge?
Post by: xox.happy1.xox on November 09, 2008, 10:16:26 pm: Yeah, loge looks nicer anyways. :) Much easier to understand in my opinion.
Title: Re: ln or loge?
Post by: Lulu on November 09, 2008, 10:38:36 pm: Just a quick question regarding logs on calculators:

How do you change the base from 'e' to something else? In catalog there's 'logbase' but i'm not too sure how to use it. I use a TI-89 btw.

thanks :)
Title: Re: ln or loge?
Post by: shinny on November 09, 2008, 10:41:10 pm: For 89's, diamond->7 gets you the log command. From there, just type log(3,2) for $log_{2} {3}$ Otherwise for 84 people, just use change of base and have ln(3)/ln(2)
Title: Re: ln or loge?
Post by: Lulu on November 09, 2008, 10:42:24 pm: perfect! thanks alot
Title: Re: ln or loge?
Post by: Captain on November 09, 2008, 10:44:04 pm: I disagree.

Writing ln(x) in place log_e is common practice.

Just go to the wikipedia article on Natural logarithm, it's plagued with ln's instead of log's
Title: Re: ln or loge?
Post by: shinny on November 09, 2008, 10:45:53 pm: Not sure if examiners take it the same way though. Teachers definitely hate it.
Title: Re: ln or loge?
Post by: brendan on November 09, 2008, 10:48:52 pm: Yes you are. No one really cares, at least in higher level mathematics.
Title: Re: ln or loge?
Post by: shinny on November 09, 2008, 10:51:09 pm: Yes but this is VCE land where writing intercepts only as numbers counts as a loss of a mark. I personally wouldn't risk it because I know my teachers definitely hated it. The risks outweigh the benefits o_o
Title: Re: ln or loge?
Post by: Captain on November 09, 2008, 10:52:26 pm: Quote from: shinjitsuzx on November 09, 2008, 10:45:53 pm
Not sure if examiners take it the same way though. Teachers definitely hate it.
Quote from: shinjitsuzx on November 09, 2008, 10:51:09 pm
Yes but this is VCE land where writing intercepts only as numbers counts as a loss of a mark. I personally wouldn't risk it because I know my teachers definitely hated it. The risks outweigh the benefits o_o

Opposite at my school. All my teachers use it.

I think it's personal preference.
Quote from: Brendan on November 09, 2008, 10:48:52 pm
Yes you are. No one really cares, at least in higher level mathematics.

Exactly.
Title: Re: ln or loge?
Post by: shinny on November 09, 2008, 10:55:02 pm: Quote from: Captain on November 09, 2008, 10:52:26 pm
Opposite at my school. All my teachers use it.

I think it's personal preference.
Well if it's personal preference, doesn't that imply theres a chance you could lose marks? Then why risk it? But whatever, do what you want. This really isn't worth arguing over -_-"
Title: Re: ln or loge?
Post by: dekoyl on November 09, 2008, 10:56:18 pm: My teacher uses $ln$ when $log_e$ is one of the terminals for an integral.
I use $ln$ when I write integrals (less cramped).
Title: Re: ln or loge?
Post by: Captain on November 09, 2008, 11:03:47 pm: Quote from: shinjitsuzx on November 09, 2008, 10:55:02 pm
Quote from: Captain on November 09, 2008, 10:52:26 pm
Opposite at my school. All my teachers use it.

I think it's personal preference.
Well if it's personal preference, doesn't that imply theres a chance you could lose marks? Then why risk it? But whatever, do what you want. This really isn't worth arguing over -_-"

No it isn't worth arguing over, and there isn't a chance of losing marks.

I've never read an examiners report saying "It was sad to see so many students lose marks on this question for the use of ln instead of log_e"
Title: Re: ln or loge?
Post by: humph on November 10, 2008, 02:42:12 am: I can never decide which one to use. If the question specifically uses $\ln$ , then I'll use that. Otherwise I usually use $\log$ .

Conveniently at university level you rarely ever have to specify $\log_e$ as you rarely work in any base other than $e$ .
Title: Re: ln or loge?
Post by: Cthulhu on November 10, 2008, 09:35:35 am: I saw $ln(x)$ on a past exam once. It should be perfectly fine.