| Author |
Comment/Response |
Daniele Lupo
|
 10/04/05 5:57pm
Hi to all.
I've a problem with the derivative of Abs.
Considering, for example, this function
a = Abs[Sqrt[s + x]]
If (with mathematica 5.1), I use this command
D[a, x]
I obtain this
Derivative[1][Abs][s + x]/(2*Sqrt[Abs[s + x]])
It containts Abs'[..] that's not right.
If I use PiecewiseExpand in this way
PiecewiseExpand[a]
I don't obtain nothing, while in this way
PiecewiseExpand[a, Reals]
I obtain
Piecewise[{{Sqrt[-s - x], s + x < 0}}, Sqrt[s + x]]
But In this case I consider all variables as real. Instead I want that x is real, while s is complex, and making an expansion with these assumptions. How can I do it?
Thanks for answers
Daniele
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