Plot2d-Question: How to plot 2 changing functionseconomically

...yeah, for sure this a solution, but is there a more practical version 
(I want to plot it over a larger range from 20 to 50).
Thank you for your help.
Michael

On 01/18/2011 12:16 AM, Richard Hennessy wrote:
> Just repeat the steps in the function as many times as you need . . .
>
> Rich
>
>
> -----Original Message----- From: Michael Heidinger
> Sent: Monday, January 17, 2011 1:45 PM
> To: Richard Hennessy
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] Plot2d-Question: How to plot 2 changing 
> functionseconomically
>
> Thank you very much, that looks great! Thanks!
> But I'm afraid i was not precious:
> I want to stay in eq1 for x seconds, than switch over to eq2, stay there
> y seconds, and then switch over to eq1 and stay there x seconds, and so
> on. I think you understand what I mean.
> How can I get this? (I think this might be a little bite more
> complicated...)
> Can you please help me!
> Michael
>
> On 01/16/2011 11:29 PM, Richard Hennessy wrote:
>> Try this, it is not very efficient but it is what you asked for.
>>
>> eq1: 'diff(I,t)=(U-R*I)/L;
>> eq2: 'diff(I,t)=-(R*I+U)/L;
>>
>> F(_t, _t0,_R,_L,_U,_eq1,_eq2):=block
>> (
>>    [_e1,_e2,_e3,_e4],
>>    _e1:ode2(_eq1,I,t),
>>    _e2:ic1(_e1, t=0, I=0),
>>    _e3:ode2(_eq2,I,t),
>>    _e4:ic1(_e3, t=_t0, I=rhs(_e2)),
>>    at(if  t < _t0 then rhs(_e2) else rhs(_e4),[t=_t,R=_R,L=_L,U=_U])
>> )$
>>
>> plot2d([F(t,4,2,6,3,eq1,eq2)],[t,0,14]);
>>
>>
>> -----Original Message----- From: Michael Heidinger
>> Sent: Sunday, January 16, 2011 12:29 PM
>> To: maxima at math.utexas.edu
>> Subject: Plot2d-Question: How to plot 2 changing functions
>> economically
>>
>> Hello,
>> first of all, i'm new to this mailing list - Please excuse my language,
>> as it's not my first.
>>
>> Well, I want to simulate an electrical circuit, which has two operation
>> condition, each of them is discribed with a diffential equation. After a
>> certain time i want to switch to the other equation.
>> 1. Equation: 'diff(I,t)=(U-R*I)/L (eg. 1 second in this operating
>> mode=t_equation1)
>> 2. Equation: 'diff(I,t)=-(R*I+U)/L (eg. 2 second in this operation
>> mode=t_equation2)
>> Well, I solved them with ode2 and ic1 for some certain points. Eg: t=0
>> and I=0. But I want to plot I for a longer periode to see how I
>> develops. I would wish myself a function where I can plot a continous
>> flow of current.
>> The function I would wish should look like
>> I(U,R,L,t,t_equation1,t_equation2).
>>
>> Dear experts, how can I construct such a function? Thank you in advance
>> for your help!
>> Michael Heidinger
>> _______________________________________________
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>> Maxima at math.utexas.edu
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>>
>
>