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Groups > comp.soft-sys.math.mathematica > #2914
| From | Roland Franzius <roland.franzius@uos.de> |
|---|---|
| Newsgroups | comp.soft-sys.math.mathematica |
| Subject | Re: Dt@x@1 |
| Date | 2011-06-02 23:12 +0000 |
| Organization | Steven M. Christensen and Associates, Inc and MathTensor, Inc. |
| Message-ID | <is95cc$61r$1@smc.vnet.net> (permalink) |
| References | <is4tgc$b3t$1@smc.vnet.net> |
Am 01.06.2011 10:33, schrieb Chris Chiasson:
> Why does Dt@x@1 return zero? I would expect it to return unevaluated.
The chain rule for Dt acting on a chain of functions of a single
argument says
Dt@x@1 = x'[1] Dt[1] ~ Dt[1]=0
Compare
Trace[Dt[x[y[w[u]]], Constants -> {u, v}]] // TreeForm
Trace[Dt[x[y[w[z]]], Constants -> {u, v}]] // TreeForm
to see that Dt[mostinnnerargument]->0 is used as a rule without
calulating superflous inner derivatives x', y', w' first.
Its of course the simplifying use of those general cancelling rules,
easy to recognize and to apply, that makes the CAS working at all (in a
limited collection of cases in finite time ;-( ).
--
Roland Franzius
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Dt@x@1 Chris Chiasson <chris.chiasson@gmail.com> - 2011-06-01 08:33 +0000
Re: Dt@x@1 "Nasser M. Abbasi" <nma@12000.org> - 2011-06-01 10:57 +0000
Re: Dt@x@1 Chris Chiasson <chris.chiasson@gmail.com> - 2011-06-02 11:15 +0000
Re: Dt@x@1 magma <maderri2@gmail.com> - 2011-06-02 11:14 +0000
Re: Dt@x@1 Chris Chiasson <chris.chiasson@gmail.com> - 2011-06-02 11:14 +0000
Re: Dt@x@1 Roland Franzius <roland.franzius@uos.de> - 2011-06-02 23:12 +0000
Re: Dt@x@1 Chris Chiasson <chris.chiasson@gmail.com> - 2011-06-04 10:20 +0000
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