Thanks very much - obviously, does the trick just fine. I suppose I'd
have stumbled across allroots eventually -- part of the learning curve
is conditioned on thinking of Maple commands by reflex (at this point).
If it isn't the same command in Maxima (no reason it should be), I make
a few educated guesses. Apparently not quite educated enough in this
instance.
Thanks again...
On 10/14/2010 11:06 AM, Stavros Macrakis wrote:
> Maxima normally gives exact symbolic solutions.
>
> To get the real roots of a polynomial, try
> float(realroots(-x^3+x+0.25) ) -- the 'float' is necessary for obscure
> historical reasons (sorry!).
>
> To get all the roots (real and complex) of a polynomial, try
> allroots(-x^3+x+0.25). Even if the roots are exactly real, allroots
> sometimes returns a tiny imaginary part.
>
> Check the documentation for more options (specifying precision etc.):
>
> ? realroots
>
> ? allroots
>
> Welcome to Maxima!
>
> -s
>
> On Wed, Oct 13, 2010 at 15:16, egc<cooch17 at verizon.net> wrote:
>> After 15+ years of using Maple, I've decided to take latest build of Maxima
>> for a spin (motivated to some degree by the desire to find a symbolic
>> algebra program I can have my students use at no cost). I've done a a bit of
>> 'fooling' with Maxima (learn by doing), and am stuck on something which
>> seems pretty trivial.
>>
>> Consider f : -x^3+x+0.25=0
>>
>> Now, I know from Maple that the roots of this polynomial are -0.83757,
>> -0.26959, and 1.1072. However, in Maxima, if I try
>>
>> solve(f,x);
>>
>> I get something is is bizarrely large and convoluted -- all sorts of
>> fractions, and square roots, and the like. I tried toggling different levels
>> of float, but I still don't end up with a nice simple solution vector
>> containing these three solutions.
>>
>> Pointers to the obvious solution? Thanks in advance (remember, newbie, more
>> or less, so set phasers to 'singe only'). ;-) I'll leave my implicit
>> differentiation question to a followup post. ;-)
>>
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>>
>>