# find point which this function is differentiable

• Dec 2nd 2008, 11:20 AM
silversand
find point which this function is differentiable
$f(x,y)=xy|x-y| , \ \ \ x,y\in R$
• Dec 2nd 2008, 11:58 AM
vincisonfire
Along x=y, the function is not differentiable.
It correspond to the "apex line" of the absolute value part.