Plot derivative of an ABS( function ) fails (RESOLVED)

[ww63]

Hello,

probably the problem is a result of the fact, that the ABS-Function leads to a not continously differntiable function. At the roots of the basic function the ABS-function creates a discontinuity!

What is the slope at x = 3 or x = 7? I think the value of the derivative at this points represented by NaN (not a number).

regards

Wolfgang