Re: [Maxima-discuss] elementary solve() problem

[Barton W. <wi...@un...>]

The Maxima solve function needs improvement. Please don't get the impression that setting an obscure variable will fix all its shortcomings.
Maybe somebody should experiment with making the default of solveradcan true.
--Barton

________________________________
From: richard christian <rp...@cl...>
Sent: Thursday, November 13, 2025 5:33 AM
To: Barton Willis <wi...@un...>
Cc: max...@li... <max...@li...>
Subject: Re: [Maxima-discuss] elementary solve() problem

Caution: Non-NU Email


Terrific. Thank you, Barton.
And needless to say, apologies for the accidental repetition in the
first 6 lines of my example...

rc

On 2025-11-13 11:23, Barton Willis wrote:
> Try setting the option variable solveradcan to true before solving:
>
>  (%i1) solveradcan : true$
>
>  (%i2) solve(n*10^(n-1)=2*n*5^(n-1),n);
>  (%o2) [n=0,n=2]
>
>  Alternatively, apply radcan before solving:
>
>  (%i1) radcan(n*10^(n-1)=2*n*5^(n-1));
>  (%o1) 2^(n-1)*5^(n-1)*n=2*5^(n-1)*n
>
>  (%i2) solve(%,n);
>  (%o2) [n=0,n=2]
>
>  For a list of additional option variables (and a bunch of other
> stuff) that affect how solve works, try
>
>  (%i3) apropos (solve);
>
> (%o3) [desolve,funcsolve,globalsolve,linsolve,linsolve_by_lu,linsolve_params,linsolvewarn,solve,solve_congruences,solvedecomposes,solveexplicit,solvefactors,
>
>  Solvenullwarn,solveradcan,solvetrigwarn,tmlinsolve,to_poly_solve]
>
>  Thanks for your interest in Maxima! If you have more questions, feel
> free to ask.
>
>  --Barton
>
> -------------------------
>
> From: richard christian <rp...@cl...>
> Sent: Thursday, November 13, 2025 3:57 AM
> To: max...@li...
> <max...@li...>
> Subject: [Maxima-discuss] elementary solve() problem
>
> Caution: Non-NU Email
>
> Apologies for this very novice question, but what am I doing wrong
> here?
> Why isn't Maxima giving n=2?
>
> (%i18)  s: t**n;
> (s)     t^n
> (%i19)  diff(s,t);
> (%o19)  n*t^(n-1)
> (%i20)  s: t**n;
> (s)     t^n
> (%i21)  diff(s,t);
> (%o21)  n*t^(n-1)
> (%i23)  ev(%,t=10) = 2*ev(%,t=5);
> (%o23)  n*10^(n-1)=2*n*5^(n-1)
> (%i24)  solve(%,n);
> (%o24)  [n=0,10^(n-1)=2*5^(n-1)]
>
> Many thanks, Richard
>
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