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Groups > comp.soft-sys.math.mathematica > #1593
| From | Peter <petsie@dordos.net> |
|---|---|
| Newsgroups | comp.soft-sys.math.mathematica |
| Subject | Re: from Rumen, MEXICO, petition |
| Date | 2011-04-11 11:07 +0000 |
| Organization | Steven M. Christensen and Associates, Inc and MathTensor, Inc. |
| Message-ID | <inund1$2e8$1@smc.vnet.net> (permalink) |
| References | <inpeua$8ul$1@smc.vnet.net> |
Am 09.04.2011 13:12, schrieb Rumen Ivanov:
> Hello,
>
> 11*Exp[-Es/135]+10.5*Exp[-Es/425]+
> 4.899*Exp[-Es/1754]+ 2.02912 = 0
> Please tell me how Mathematica can solve this equation
> for Es? With the derivatives of "Solve" it is impossible.
>
> Best
>
> Regards,
>
> Rumen
>
> Prof. Dr. Rumen Ivanov Tsonchev
> Facultad de F=EDsica
> Universidad Aut=F3noma de Zacatecas
> e-mail=B4s:
> rumen5252@yahoo.com.mx
> rumen@fisica.uaz.edu.mx
Hello Rumen,
as has been said, there is no real solution, but to make things easier
for Mathematica, I took the Log of the Exp-sum and set it equal to
Log[-2.02912]. Then FindRoot gets an approx. solution:
In[1]:= expr=11*Exp[-Es/135]+10.5*Exp[-Es/425]+4.899*Exp[-Es/1754]+2.02912;
eqn = Log[expr - 2.02912] == Log[-2.02912];
{Es, expr} /. First @ FindRoot[eqn, {Es, 0}, MaxIterations->Infinity]
Out[3]= {298.34 -1494.67 I, 1.77636*10^-15 + 0. I}
Regards,
Peter
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from Rumen, MEXICO, petition Rumen Ivanov <rumen5252@yahoo.com.mx> - 2011-04-09 11:12 +0000 Re: from Rumen, MEXICO, petition Peter <petsie@dordos.net> - 2011-04-11 11:07 +0000 Re: from Rumen, MEXICO, petition Noqsi <noqsiaerospace@gmail.com> - 2011-04-11 11:07 +0000 Re: from Rumen, MEXICO, petition "Stephen Luttrell" <steve@_removemefirst_stephenluttrell.com> - 2011-04-11 11:05 +0000
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