1. ## log vs ln

Hello,

I have never really understood the difference between the log and the ln function. Both are logarithmic functions. How do you know when to use which?

/Jones

2. Originally Posted by Jones
the difference between the log and the ln function. Both are logarithmic functions. How do you know when to use which?
Anyone can start a real disagreement started with that question.
It is fair to say that historically log has referred to base 10 logarithms whereas ln has referred to base e logarithms called the natural logarithm. However, some mathematicians have of late suggested that we use log for all logarithms and use the base e as the normal base. Notably, that is the position of Leonard Gillman. In fact, I was present at one meeting where he advocated that and I watched the heated discussion that followed. I must say that his arguments convinced me that he is right. In fact, if you see the calculus text by Gillman & McDowell that is the convention in that book.

3. Originally Posted by Jones
I have never really understood the difference between the log and the ln function. Both are logarithmic functions. How do you know when to use which?
Other than the bases being different, they're pretty much the same thing, and of course you can use the change-of-base formula to convert between the two.

Unless you are told which log to use, the choice should be up to you.

4. You may use which ever is best suited for your specific case.

For clarity you must define your base.

11*11 = 1001

That should seem obvious to most.
But some will insist that this is using binary.
Thus the base 2 is used.

My preference is ln

It is shorter.