Re: Try again to send my message: problems about "for"
- To: mathgroup at smc.vnet.net
- Subject: [mg96571] Re: Try again to send my message: problems about "for"
- From: dh <dh at metrohm.com>
- Date: Mon, 16 Feb 2009 16:38:03 -0500 (EST)
- References: <gnbkaa$3cg$1@smc.vnet.net>
Hi Laura,
curly bracket are used to denote lists not bracketing, you must use
"(..)" for bracketing. Therefore "{-2+C1}==1" is not an equation.
Then, the function DE is not defined.
Further, a compound statement uses ";" as delimiter, not ",".
There is no {..} needed inside the For loop:
Fot[ ..; ..; ... ,++i]
hope this helps, Daniel
laura parisi wrote:
> Dear Mathematica Users,
> the last message was unreadable and so i send it again.
>
>
> I've realized a loop using Euler method:
> For[i = 1, i < 2,
> {S = (1/2)*(N1^2/DE[i - 1]) - (1/2)*DE[i - 1]*\[Epsilon]rif^2,
> a[i] = DSolve[Derivative[1][\[Rho]][t] - S == 0, \[Rho][t], t],
> \[Rho][t] = \[Rho][t] /. a[i],
> \[Rho][t] = \[Rho][t] /. C[1] -> C1,
> eq = \[Rho][t] /. t -> (t1[[i]] - 1),
> a = Solve[eq == \[Rho][i - 1], C1],
> \[Rho][i] = \[Rho][t] /. {C1 -> a, t -> t1[[i]]},
> DE[i] = DE[i - 1]*\[Rho][i]}; i++];
>
> in this expression, N1 is stated like a sinusoidal function:
> N1 = N0 + B*Sin[\[Omega]*t];
>
> and T1 is a vector of time:
> t1 = Table[i, {i, 20}]
>
> All the other parameters are allocated:
> B = 1;
> N0 = 2;
> \[Omega] = 1;
> A = 1;
> E0 = 1;
> \[Rho][0] = 1;
> \[Epsilon]rif = 1;
>
> The loop give me this error:
> Solve::eqf:{-2+C1}==1 is not a well-formed equation. >>
>
> with C1 constant of integration.
>
>
> What can I do for this loop in this case and in a case if i want to
> reapet the loop for i<100?
> Is better to use "DO"?
>
>
> Help me..It's important.
>
> Thank you!
>