# arc length example

## Primary tabs

Synonym:
logarithm of sine function
Type of Math Object:
Example
Major Section:
Reference
Parent:
Groups audience:

## Mathematics Subject Classification

### "ln" in pstricks

Hi, I would like to add a pstricks graph to
http://planetmath.org/encyclopedia/ArcLengthExample.html
but I cannot implement for it the logarithm operator. Who could help?
Jussi

### Re: "ln" in pstricks

Can you say a little more about what you are trying to do and what is not working?

Roger

### Re: "ln" in pstricks

Dear Roger,
It seems that pstricks don't know the logarithm operators "ln" and "log". I have now made a simple test code in the entry -- you can see that logarithms don't work. Other operators, as "sin", "exp" etc., function well.
Jussi

### Re: "ln" in pstricks

Actually, if you look at the error messages closely, you will see that the problem is not with pstricks (PostScript does have a "ln" operator), but rather PM's automatic linking to the word "ln" is interfering. So you can just suppress the automatic linking and the diagram will work.

Steve

// Steve

### Re: "ln" in pstricks

Steve, you are fully right -- thank you very much!
I still wonder why the system doesn't allow to continue the logsin curve to the interval [Pi/2, Pi].
Regards,
Jussi

### Re: "ln" in pstricks

> Steve, you are fully right -- thank you very much!
> I still wonder why the system doesn't allow to continue the
> logsin curve to the interval [Pi/2, Pi].

Sorry, no idea.