Arduino Language Reference section describes abs() as follows:

abs(x)

DescriptionComputes the absolute value of a number.

Parameters

x: the number

Returns

x: if x is greater than or equal to 0.

-x: if x is less than 0.

Since when can an absolute value of a number return a negative number? I am a middle aged person; Is this the “new” math???

As described, this abs() function does nothing. Furthermore, I do not believe this is a “typo” in the description. When you use this function in a sketch, it does return a value of x as described. if x>=0, abs(x) returns x; if x<0, abs(x) returns a negative number.

What am I not understanding here?