problems using solve with functions



I think that, solve is using a linear equation solver, and your 
equations are not linear in x.
Even if solve were to use a polynomial system solver, your equations are 
not polynomial in x.

How about solving for sin(x), getting a result like sin(x)=1, and then 
solving that?

Should Maxima do this automatically?  Maybe.  It looks a little 
ticklish.  Since there
are an infinite number of solutions to sin(x)=1, how does 
back-substitution work?

RJF


On 11/25/2012 7:57 AM, Norman Werner wrote:
> Hello,
>
> I am using maxima as a common-lisp library for a pet-project of mine.
> However I stumbled upon a problem when using solve.
>
> I try to solve an equation or a set of equation and I do introduce 
> known variables by
> adding an appropriate equation to the set. Eg:
>
>      solve([1=a*x,a=1],[a,x]);
> -> [[a = 1, x = 1]]
>
> Which works fine! If the equation however contains functions like exp, 
> log, or sin solve won't find any solutions:
>
> solve([1=a*sin(x),a=1],[a,x]);
> ->                            []
> solve([1=a*log(x),a=1],[a,x]);
> ->                            []
> (%i125) solve([1=a*exp(x),a=1],[a,x]);
> ->                            []
>
> Obviously the solutions to those problems are not as obvious as they 
> seem. Could someone clarify this behaviour? What's the correct way to 
> solve such problems with maxima?
>
> Thanks
>
> Norman
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