# Math Help - Natural log notation

1. ## Natural log notation

I'm a bit confused, if
$y= e^x$
then $x = log_{e}y$
$log_{e} = ln$
$x = log_{e}y = lny$
So why is the natural log always shown as $lnx$ and not $lny ?$

2. Originally Posted by hciR
I'm a bit confused, if
$y= e^x$
then $x = log_{e}y$
$log_{e} = ln$
$x = log_{e}y = lny$
So why is the natural log always shown as $lnx$ and not $lny ?$
You can take the natural log of x, y or any other pronumeral you want. It is not restricted only to x. So I don't see what your problem is.

3. I think it's just the way my book explains it is confusing me, do you know a free graphing software that can plot exponentials? I have one called mathGV but it can't do them.

4. As MF said you can take the natural log of any pronumeral you wish.

In most textbooks I have seen, a lot of the questions are in the form $y = f(x)$, this means y is equal to a function of x. A lot of natural log questions therefore are along the lines of $y = \ln{x} + somethingelse$.

This will be the reason that the majority of questions you have seen are $\ln{x}$, not $\ln{y}$.