Re: Problems with Module
- To: mathgroup at smc.vnet.net
- Subject: [mg112069] Re: Problems with Module
- From: Tomas Garza <tgarza10 at msn.com>
- Date: Sat, 28 Aug 2010 07:03:43 -0400 (EDT)
I think you're using an invalid notation for your derivatives. The on-line help uses a straight ' to denote a derivative (q.v.). For the texts you had better use the writing assistant palette, special symbols, and you'll find a prime and a double prime symbol.
Making these changes, I get a clean result for t == 0, but as soon as the slider is moved an error is reported, which has to do with your code, I guess.
Saludos,
Tomas
> Date: Fri, 27 Aug 2010 04:07:29 -0400
> From: sterraza at uacj.mx
> Subject: [mg112052] Problems with Module
> To: mathgroup at smc.vnet.net
>
> Hi!
>
> The following is a slight modification of a code that works fine. But this
> one does not work.
> However, if I empty the list of local variables in Module, Then it works!
> Could some of you enlighten me?
>
> f[t_]:==4 Sin[t];g[t_]:==2 Cos[t];a==0;b==2\[Pi];
> DerVectConst[f,g,a,b]
>
> DerVectConst[f_,g_,a_,b_]:==Module[{r,vel,acel,unitario,derivadadeu,du},
> $Assumptions==t\[Element]Reals;
>
> r[t_]=={f[t],g[t]};
> vel[t_]==(r^\[Prime])[t];
> acel[t_]==(r^\[DoublePrime])[t];
> unitario[t_]==acel[t]/Norm[acel[t]];
> derivadadeu[t_]==(unitario^\[Prime])[t];
> du[t_]==derivadadeu[t]//FullSimplify;
>
> Manipulate[
>
> f1==Graphics[{Thick,Blue,Arrow[{r[t],r[t]+du[t]}]}];
> f2==Graphics[{Thick,Green,Arrow[{r[t],r[t]+unitario[t]}]}];
> g1==ParametricPlot[r[t],{t,a,b},AspectRatio->Automatic,PlotStyle->{Thick, Red}];
> txt==Graphics[{Text[Style["\!\(\*OverscriptBox[\"u\",
> \"^\"]\)",18,Bold],(r[t]+1.1unitario[t])],Text[Style["\!\(\*OverscriptBox[\"u\",
> \"^\"]\)^\[Prime]",18,Bold],(r[t]+1.1du[t])]}];
> punto==Graphics[{PointSize[.02],Point[r[t]]}];
> Show[g1,f1,f2,txt,punto,PlotRange->All]
> ,{t,a,b}]
> ]
>