Re: How to calculate the partial derivative?

*To*: mathgroup at smc.vnet.net*Subject*: [mg128751] Re: How to calculate the partial derivative?*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Fri, 23 Nov 2012 03:27:53 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20121122004814.D4F1A6894@smc.vnet.net>

When Simplify doesn't work try FullSimplify. k35 = 1/180 (-b1 b3 - b2 b3 - c1 c3 - c2 c3 - d1 d3 - d2 d3); k35 = k35 // FullSimplify (1/180)*((-(b1 + b2))*b3 - (c1 + c2)*c3 - (d1 + d2)*d3) Bob Hanlon P.S. I am not a professor. On Thu, Nov 22, 2012 at 8:24 PM, Tang Laoya <tanglaoya1989 at gmail.com> wrote: > Dear Prof. Hanlon, > > Thank you very much for your quick reply. > > It is strange that your commands works but mine doesn't work: > > k35 = 1/180 (-b1 b3 - b2 b3 - c1 c3 - c2 c3 - d1 d3 - d2 d3) > k35 = k35 // Simplify > > The outputs are: > 1/180 (-b1 b3 - b2 b3 - c1 c3 - c2 c3 - d1 d3 - d2 d3) > 1/180 (-b1 b3 - b2 b3 - c1 c3 - c2 c3 - d1 d3 - d2 d3) > > respectively. > > Could you please help me to take a look at it? > > > Thanks, > Tang Laoya > > > On Fri, Nov 23, 2012 at 9:12 AM, Bob Hanlon <hanlonr357 at gmail.com> wrote: >> >> 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 > >

**References**:**How to calculate the partial derivative?***From:*Tang Laoya <tanglaoya1989@gmail.com>