Hello.
On page http://www.arduino.cc/en/Reference/Abs
It says the ABS function will return:
x: if x is greater than or equal to 0.
-x: if x is less than 0.
This is a bit unclear! Now, I realise that if x is negative, then -x is positive, but not everyone will so this is a bit too confusing.
Why not simply say:
The abs(x) function returns the absolute value of x, that is to say it returns x without the sign.
and provide some examples :
x= 4.5 returns 4.5
x= -3.2 returns 3.2
x= 0 returns 0
Hope that can be updated. 
Warmest regards,
Brian
Paul_B
2
Well firstly, your chance of having anything in the tutorials/ references altered, is close to |x| = -(x2).
However the definition
x: if x is greater than or equal to 0.
-x: if x is less than 0.
is actually entirely accurate in terms of the function's implementation.
system
3
You're not the first to (incorrectly IMO) report this one. 
Hello,
bcraigie:
Hope that can be updated.
Create an issue here...
Optionally...
Fork the repository...
Change abs.adoc...
Commit the change. Create a pull request.
Thanks Coding Badly, I shall follow your instructions.
Re: AWOL, how can it be incorrect to want to clarify or improve the documentation?
Thanks everyone.
Warmest wishes,
Brian