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Re: Problems about "For"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg96548] Re: Problems about "For"
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Mon, 16 Feb 2009 06:56:47 -0500 (EST)
  • Organization: The Open University, Milton Keynes, UK
  • References: <gn8j97$7md$1@smc.vnet.net>

In article <gn8j97$7md$1 at smc.vnet.net>,
 laura parisi <lau.parisi at gmail.com> wrote:

> Dear Mathematica Users,
> 
> I've realized a loop using Euler method:
> 
> For[i=1,i<2,
>   {S=1/2*N12/DE[i-1]-1/2*DE[i-1]*=83=D5rif2,
>    a[i]=DSolve[=83=E2'[t]-S=83=FA0,=83=E2[t],t],=83=E2[t]==83=E2[t]/.a[=
> i],
>    =83=E2[t]==83=E2[t]/.C[1]=84_C1,
>    eq==83=E2[t]/.t=84_(t1[[i]]-1),
>    a=Solve[eq===83=E2[i-1],C1],
>    =83=E2[i]==83=E2[t]/.{C1=84_a,t=84_t1[[i]]},DE[i]=DE[i-1]*=83=E2[i]}=
> ;i++];
> 
> in this expression, N1 is stated like a sinusoidal function:
> N1=N0+B*Sin[=83=E7*t];
> 
> and T1 is a vector of time:
> t1=Table[i,{i,20}];
> 
> All the other parameters are allocated:
> B=1;
> N0=2;
> =83=E7=1;
> A=1;
> E0=1;
> =83=E2[0]=1;
> =83=D5rif=1;
> DE[0]=1;
> 
> The loop give me this error:
> 
> Solve::eqf :  {-2+C1}=83=FA1 is not a well-formed equation. =83=F7
> with C1 constant of integration.
> 
> 
> What can I do for this loop in this case and if i want to reapet the
> loop for i<100?
> Is better to use "DO"?
> 
> 
> Help me..It's important.
> 
> Thank you!

Laura,

Your message is unreadable on my different systems (Mac OS X, Windows, 
and Linux, web browsers Safari, Firefox, or Chrome, or news reader 
MT-NewsWatcher) for it is crippled by to many non-rendered characters 
such as =84 or =83=E2. (Of course, other readers might have a different 
experience.)

You should try to copy and past Mathematica expressions in InputForm[],
for it is way more readable and far less prone to misinterpretation
(especially when your email/newsgroup client adds spurious equal sings
and/or other unwanted characters or character conversions).

To use the _InputForm_ when copying an expression from a Mathematica
notebook to an email client: select the cell(s) you want to include in
your email, then within the *Cell* menu select either *Convert To* or
*Display As* and choose *InputForm*. Finally, copy and paste as usual.

Regards,
--Jean-Marc


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