very slow solving of x^2-sqrt(2*x)+20=0



Yes, it helps in this example. Thank you.

It is interesting (and useful)  to know the reason of very slow processing
of the initial query!

2010/4/6 Sheldon Newhouse <sen1 at math.msu.edu>

> On 04/06/2010 08:24 AM, Mihail Denisenko wrote:
>
>> Hi,
>>
>> If we use function algsys to solve equation x^2-sqrt(2*x)+20=0, then it
>> takes too much time.
>>
>> (%i16)  algsys([x^2-sqrt(2)*y+20=0, x=y^2],[x,y]);
>> (%o16)                                []
>>
>> Function algsys returns answer approximately in 30 seconds. Usually algsys
>> 10-30 times faster.
>>
>> Is it correct? Is it possible to fix that issue?
>>
>> Best regards,
>> Mihail D
>>
>>
>>
>>  If you remove the square root, say, in the first equation:
>  solve(2*x=(x^2+20)^2,x);
>
> then the answer comes back very fast.  Of course, you get answers for
> +sqrt(2*x) and -sqrt(2*x).
>
> -sen
>



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