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MathGroup Archive 2005

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Problems with Derivative, Piecewise, Assuming

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55898] Problems with Derivative, Piecewise, Assuming
  • From: Enrique Zeleny <ezeleny at fcfm.buap.mx>
  • Date: Sat, 9 Apr 2005 03:55:49 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com


Evaluate each one of the following inputs (the derivative isnt defined in
any point)

D[Log[-Abs[Sin[x]]], x]

D[Piecewise[{{Log[Sin[x]], Sin[x] < 0}, {Log[-Sin[x]], Sin[x] > 0}}], x]

Assuming[x \[Element] Reals, D[Log[-Abs[Sin[x]]], x]]

Assuming[x \[Element] Complexes, D[Log[-Abs[Sin[x]]], x]]

Assuming[x \[Element] Reals, D[Piecewise[{{Log[Sin[x]], Sin[x] < 0},
     {Log[-Sin[x]], Sin[x] > 0}}], x]]

Assuming[Sin[x] > 1 && x \[Element] \[DoubleStruckCapitalR],
  D[Piecewise[{{Log[Sin[x]], Sin[x] < 0}, {Log[-Sin[x]], Sin[x] > 0}}],
x]]


Future work for Mathematica developers


Thanks


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