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[Neonivek]

So right now my biggest hurdle in my math is simply natural log. I have no idea what it is used for or even how it is used inspite taking a class with a heavy focus on it before.

It just doesn't make sense to me especially in light of... well... Log...

Is there a easier way you learned to understand it or an online source dedicated to LN my arch nemesis? (And not Lawful Neutral Jokesters)

[Karlito]

Have you taken Calculus yet? It actually doesn't make too much sense in then. Otherwise all you need to know is that it's a logarithm of base e.

Wasn't there a generic math help thread recreated recently?

[Zrk2]

To the New Math Help Thread with you!

/shameless plug

[Neonivek]

To the New Math Help Thread with you!

/shameless plug

Yeah... this is kinda asking for... "What is Natural Log? What is it used for?"

[Zrk2]

Sshh you! I'm busy plugging my new thread. We don't need your facts here! This is ADVERTISING!

Also a natural log is a log with a base of e, a constant that you can't memorize as it goes on forever like pi, however most scientific calculators have a button that lets you use it.

[Neonivek]

Sshh you! I'm busy plugging my new thread. We don't need your facts here! This is ADVERTISING!

Also a natural log is a log with a base of e, a constant that you can't memorize as it goes on forever like pi, however most scientific calculators have a button that lets you use it.

Not only are calculators not allowed... but they don't want me to calculate natural log anyway.

[Lectorog]

The natural log is a magical value, but its magic isn't really evident outside of calculus and probability. Out there it's just a log with the base of 'e', a long pointless number. Know that ln(e) = 1, and e^ln(1) = 1, like with any logarithm.

Do you not understand the 'e' part, or the logarithm part?

[rutsber]

If you aren't sure how it's useful, outside of calculus it becomes useful with exponential decay. When I learned about it in advanced algebra, we used exponential decay as a way to practice it. If you are wondering what it is, it's just a logarithm with a base of e as opposed to 10 with a common logarithm. If you aren't sure what a logarithm is, I can elaborate on that as well.

[mainiac]

Original Poster is most likely victim of the fact that we aren't very good at teaching mathematics as a society.  Highschoolers get taught what a natural log is long before they learn why natural logs are important.  It would be like asking someone who doesn't know what a circle is to memorize digits of Pi.

So pretty much just remember that it's log to the power 'e' and understand that natural logs become much more useful once you get to calculus.  They are so useful that "log" becomes synonymous with "natural log" once you reach a high enough level.  Once you learn derivatives and integrals suddenly natural logs will make a lot more sense.

[Grek]

The derivative of the function F(x) (where F(x) stands in for any function, could be y=x, could be y=x^10 - 3x^2 +4) is a second function, G(x), that gives the slope of F(x) for any given value of x. Euler's constant e is important because when F(x)=ln(x), G(x)=1/x and when F(x)=e^x, G(x)=e^x as well. This is much much easier to work with than F(x)=log10(x) or F(x)=10^x, both of which produce an ugly mess when you take the derivative of them.

That said, ln(x) works just like log10(x) and log2(x) for most purposes. ln(x)*ln(y)=ln(x+y) and all that still applies regardless of what base you use.

[Thief^]

You can take a logarithm of a number to any base by dividing the logarithm (in any base) of the number by the logarithm (in the same base) as the base you want.

i.e.
log₂(13) = log_e(13) / log_e(2)

log₂ is useful in computing because (rounded up) it tells you how many bits are needed to store a number, and the above identity comes in handy as most calculators and programming languages don't have a log₂ function.


Logarithms used to be a lot more important, with a slide ruler or a few tables of logarithms, you could very quickly multiply two numbers, or raise one number to a power of another, etc, without a calculator, and to a very high precision.
For multiplying: Take the logarithm of your two large numbers (i.e. look them up on the log tables), then add the logs, and then raise the base (e or 10 normally) to that sum (i.e. look the sum up on the log table). The result is your answer. Division just becomes subtraction.

For raising to a power, you take the logarithm of your first number, multiply that by the 2nd number, and then take e to the power of that to get the final result. You could even do *that* multiplication with a log table if it was a partiularly large power.

[eerr]

Why don't you just search for "why natural log" or something.

It's not thaaaat hard to find things.

[Neonivek]

Why don't you just search for "why natural log" or something.

It's not thaaaat hard to find things.

Because I know what natural log is, I know what it is used for... I don't understand it and I cannot naturally use it.

I was hoping for tips that people have used personally and more down to earth explanations.

[Karlito]

Why don't you just search for "why natural log" or something.

It's not thaaaat hard to find things.

Because I know what natural log is, I know what it is used for... I don't understand it and I cannot naturally use it.

I was hoping for tips that people have used personally and more down to earth explanations.

In what context are you trying to use it? I'm not really sure what your confusion is.

[ed boy]

Why don't you just search for "why natural log" or something.

It's not thaaaat hard to find things.

Because I know what natural log is, I know what it is used for... I don't understand it and I cannot naturally use it.

I was hoping for tips that people have used personally and more down to earth explanations.

It's the inverse of exponentiation. Whenever you want to un-exponentiate something, you use it.