Derivative of modulus of a function

[nil1996]

how do we take derivative of modulus of a function??

 

[tiny-tim]

hi nil1996!

|f(x)| = f(x) times sign(f(x))

so you can use the product rule, except where f(x) = 0 (where |f|' won't exist unless f' = 0)

 

[brmath]

Are you talking about a function of a real or complex variable?