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Re: How to calculate the partial derivative?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg128747] Re: How to calculate the partial derivative?
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Fri, 23 Nov 2012 03:26:33 -0500 (EST)
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  • References: <20121122004814.D4F1A6894@smc.vnet.net>

Use Simplify; however, the specific resultant form is determined by
the canonical order of the variables.

bb1 = -Det[{{1, 1, 1}, {y2, y3, y4}, {z2, z3, z4}}] // Simplify

y4 (-z2 + z3) + y3 (z2 - z4) + y2 (-z3 + z4)


-Det[{{1, 1, 1}, {y2, y3, y4}, {x2, x3, x4}}] // Simplify

x4 (y2 - y3) + x2 (y3 - y4) + x3 (-y2 + y4)


Bob Hanlon


On Thu, Nov 22, 2012 at 7:23 PM, Tang Laoya <tanglaoya1989 at gmail.com> wrote:
> Dear Prof. Hanlon,
>
> Thank you very much for your kindly reply for my previous question.
>
> Now I have another question about factor:
>
> I wish mathematica give me an express which I can coding by Fortran with
> smallest number of floating operations. For example, if I have:
>
> bb1 = -Det[{{1, 1, 1}, {y2, y3, y4}, {z2, z3, z4}}];
>
> the result by mathematica is:
> y3 z2 - y4 z2 - y2 z3 + y4 z3 + y2 z4 - y3 z4
>
> I wish it output the result like this:
> z2 (y3-y4) - z3 (y2-y4) + z4 (y2-y3)
>
>
> What should I do?
>
>
> Thanks,
> Tang Laoya



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