Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: quadratic multiplication

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84295] Re: quadratic multiplication
  • From: KFUPM <hussain.alqahtani at gmail.com>
  • Date: Mon, 17 Dec 2007 19:22:12 -0500 (EST)
  • References: <fk2v35$n96$1@smc.vnet.net> <fk5akt$5jc$1@smc.vnet.net>

On Dec 17, 11:05 am, dh <d... at metrohm.ch> wrote:
> Hi,
>
> we may create a rule that sets all products of u^s to zero:
>
> mem[y_]:=MemberQ[{u1,u2,u3,u4,u5,u6},y];
>
> rules={y1_ y2_/;mem[y1]&&mem[y2]->0,y_^_/;mem[y]->0};
>
> here is an example:
>
> c1 u1+c2 u2+ c15 u1 u5 + c146 u1 u4 u6 /. rules
>
> hope this helps, Daniel
>
>
>
> KFUPM wrote:
> > Dear all
>
> > I have a very large expression which involves the multiplication of
> > these variables:
>
> > var ={u1,u2,u3,u4,u5,u6} with some other constants. In the expression,
> > i want to suppress any quadratic or higher order multiplication of
> > these varibles , e.g u1*u5  or u1*u4*u6 should be zero. And since, my
> > expression is huge, i want to do this automatically. Any help in this
> > regard is highly appreciated.
>
> > Sincererly yours,
>
> > HMQ- Hide quoted text -
>
> - Show quoted text -

Thanks for your reply.

The rule didn't work for this term:

Out[103]=
\!\(\*
  RowBox[{\(5\/2\), " ", \(b\^4\), " ", \(x[2]\^4\), " ",
    RowBox[{
      SuperscriptBox["u11",
        TagBox[\((1, 0, 0)\),
          Derivative],
        MultilineFunction->None], "[", \(x[1], x[3], t\), "]"}], " ",
    RowBox[{
      SuperscriptBox["u13",
        TagBox[\((1, 0, 0)\),
          Derivative],
        MultilineFunction->None], "[", \(x[1], x[3], t\), "]"}]}]\)

Please note that b is a constant. So the varibles are only u11 u13.

I appreciate your help in this regard.

Thanks in anticipation.



  • Prev by Date: Conditionals -- what is "fastest" way to evaluate
  • Next by Date: Re: Re: Speeding Up Realtime Visualization
  • Previous by thread: Re: quadratic multiplication
  • Next by thread: Re: quadratic multiplication