The reference page does not include the log functions.

AFAIK, all functions defined in the mathematics library in AVR LibC are avaliable: avr-libc: <math.h>: Mathematics.

One thing to note is that all floating point variables, both float and double, are 32 bits.

The **[u]reference page[/u]** does not include the log functions.

I'm glad you posted this question - I had been looking for the log function also and could not find it in reference section. Now because of your thread, I find it in the link - just hope it works when I try to use it later tonight or this weekend.

Ken H>

you're right, it isn't in the listed functions. however, they are supported (or at least arduino compiles with them in the code).

for log base 10, the syntax is log10(input);

for natural log (ln), it's log(input);

maybe somebody should edit the listed functions in the reference section to include this; it seems like it would be used commonly.

I apologize, I apparently have no idea what I'm talking about. log(x) works, but log10(x) does nothing.

I think a workaround may be to do this: If you want to find log base 10 of X, then you can do the natural log of X over the natural log of 10. so in english, logX = lnX/ln10. in arduino, it is

```
log(x) / log(10);
```

I'm not sure, however.

Code:

`log(x) / log(10);`

I'm not sure, however.

But you are right :)

I noticed that it lacks in the keywords.txt file (for arduino 0017 at least, I think also in 0018). It is only a matter of adding an entry below the "# KEYWORD2" section:

```
log KEYWORD2 Log
```

Not a big deal though, but it's nice to have the syntax colour right.