# [Maxima] Trouble in Solving Equation

Lorenzo Isella lorenzo.isella at gmail.com
Wed Apr 18 15:10:26 CDT 2012

```Hello,
And sorry for the late reply.
Indeed the problem was an extra line.
The snippet

Rg:(N/kf)^(1/df);
Rm:0.512*(1-1/log(2*N))*Rg+0.72*N^0.413;
Req:N^(1/3);
phi:N/Rgeo^3;
myeq: Rm/Rgeo = c*Rg/Rgeo+d;
solve(myeq, Rgeo);

does exact what I need.
Cheers

Lorenzo

On Sat, 31 Mar 2012 05:54:52 -0500
Barton Willis <willisb at unk.edu> wrote:

> -----maxima-bounces at math.utexas.edu wrote: -----
>
> > Rg:(N/kf)^(1/df);
> > Rm:0.512*(1-1/log(2*N))*Rg+0.72*N^0.413;
> > Req:N^(1/3);
> > phi:N/Rgeo^3;
> > Rm/Rgeo: a*Rg/Rgeo+b;
> > myeq: Rm/Rgeo = c*Rg/Rgeo+d;
> > solve(myeq, Rgeo);
>
> The assignment Rm / Rgeo : a*Rg/Rgeo+b does something, but maybe it doesn't do what you think it does.
> To read the user documentation for assignment, enter ? :.
>
> Just guessing, maybe you want:
>
> (Rg:(N/kf)^(1/df),
>  Rm:0.512*(1-1/log(2*N))*Rg+0.72*N^0.413,
>  Req:N^(1/3),
>  phi:N/Rgeo^3,
>  myeq: Rm/Rgeo = c*Rg/Rgeo+d,
>  solve(myeq, Rgeo));
>
> And this works OK, I think. Let us know if this doesn't resolve your question.
>
> --Barton
>
>
>
```