Dear Leo,
thanks for the help. In my case, I get:
(%i5) solve(first(%o5)/a,a);
first: argument must be a non-atomic expression; found %o5
-- an error. To debug this try: debugmode(true);
The other option
solve(log(TGW)=log(TRRV),a), logexpand=all;
leads to something...
But could you explain me what you did? What does first(%o5)/a mean?
And why does the log help?
The reply starts with
3146 log(Rinfl) gamma 6292 log(M + m)
(%o6) [a = expt(%e, --------------------- - ------------------
3146 gamma - 25168 3146 gamma - 25168
....
What does that %e mean?
I suppose the answer is the exponent of the log?
thanks!
On 13 March 2012 14:58, Leo Butler <l_butler at users.sourceforge.net> wrote:
> Pau <vim.unix at googlemail.com> writes:
>
>> Thanks... however something seems strange... it looks like maxima is
>> trying to simplify the expression and in the end I get
>>
>> ? ? ? ? ? ? ? ? ? ? ? ? ? 3 - gamma
>> ? ? ? ? ? ? ? ? ? ? 3/8 - --------- ? ? ? ? ? ? ? ? ? ? ? ? ?3 ? ? ? ?3
>> ? ? ? ?1/4 ? ? ? ? ? ? ? ? ? ?8 ? ? ? ? ? ? 2 ? ? ? ? ? ? ? G ?M + m G ?1/4
>> ? ? 4 6 ? ?sqrt(7) a ? ? ? ? ? ? ? ?sqrt(2 e ?+ 1) sqrt(M) (-----------)
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?c
>> a = -----------------------------------------------------------------------]
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? gamma - 3
>> ? ? ? ? ?5/4 ? ? ? ?4 ? ? ? ?2 ? ? ?1/4 ?Rinfl ? ? ? ? ?M 1/8 ? ? ?1/8
>> ? ? ? ? 5 ? ?c (37 e ?+ 292 e ?+ 96) ? ?(----------------) ? ?(G M)
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? m
>>
>>
>> (I hope that the alignment is right)
>>
>> As you can see, there's an "a" in the right hand side... that's strange
>>
>> I did this:
>>
>> (%i1) Fe : 1 + (73/24)*e^2 + (37/96)*e^4$
>>
>> (%i2) Na : (M/m) * (a/Rinfl)^(3-gamma)$
>>
>> (%i3) TGW : (5/64) * (c^5/G^3) * a^4/(m*M * (m + M)) * Fe$
>>
>> (%i4) TRRV : a^(3/2)/(sqrt(G*M)) * M/m * (0.28*(e^2+0.5))^2/sqrt(Na)$
>>
>> (%i5) solve(TGW=TRRV,a);
>>
>> Any idea of what might have gone wrong?
>>
>> thanks
>
> For some reason, solve gave up and returned a partial answer.
> Here are a couple ideas:
>
> solve(first(%o5)/a,a);
>
> solve(log(TGW)=log(TRRV),a), logexpand=all;
>
> Both give me an answer.
>
> Btw, gamma is the name of a function in Maxima. Although variables and
> functions may share the same name, this will likely lead to obscure and
> wierd errors, so it is better to use another name.
>
> Leo
>
>>
>> On 12 March 2012 00:56, Leo Butler <l_butler at users.sourceforge.net> wrote:
>>> Pau <vim.unix at googlemail.com> writes:
>>>
>>>> Hi,
>>>>
>>>> I am sorry for a rather trivial question... If I have two equations like
>>>>
>>>> T(a,e) = a^4 ( 1 - e^3)
>>>> H(a,e) = e^3 * constants * a^(-1)
>>>>
>>>> and I want to find the values of a ,e that equate them
>>>>
>>>> T(a,e) = H(a,e) ?---> a = XXXX f(e)
>>>
>>> Try
>>> ? solve
>>> at the Maxima command line.
>>>
>>> A couple notes:
>>> -the assignment operator in Maxima is :
>>> -the function definition operator is :=
>>> -to solve your problem,
>>> ?I did
>>>
>>> (%i1) T : a^4*(1 - e^3) $ H : c*e^3/a $ display2d : false $
>>>
>>> (%i4) solve(T=H,e);
>>>
>>> (%o4) [e = (sqrt(3)*%i-1)*a^(5/3)/(2*(c+a^5)^(1/3)),
>>> ? ? ? e = -(sqrt(3)*%i+1)*a^(5/3)/(2*(c+a^5)^(1/3)),
>>> ? ? ? e = a^(5/3)/(c+a^5)^(1/3)]
>>>
>>>>
>>>> how could I do this in maxima? The best would be an example.
>>>>
>>>> Thanks for this nice piece of software. I am looking forward to
>>>> learning how to use it in detail. Looks very promising.
>>>>
>>>> Cheers,
>>>>
>>>> Pau
>>>> _______________________________________________
>>>> Maxima mailing list
>>>> Maxima at math.utexas.edu
>>>> http://www.math.utexas.edu/mailman/listinfo/maxima
>>>>
>>>
>>> --
>>> Leo Butler ? ? ? ? ? ? ? ?<l_butler at users.sourceforge.net>
>>> SDF Public Access UNIX System - ? http://sdf.lonestar.org
>> _______________________________________________
>> Maxima mailing list
>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>>
>>
>
> --
> Leo Butler ? ? ? ? ? ? ? ?<l_butler at users.sourceforge.net>
> SDF Public Access UNIX System - ? http://sdf.lonestar.org