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Re: How can I make the NSolve output the roots meeting

• To: mathgroup at smc.vnet.net
• Subject: [mg86460] Re: [mg86446] How can I make the NSolve output the roots meeting
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Wed, 12 Mar 2008 00:09:35 -0500 (EST)
• Reply-to: hanlonr at cox.net

eqn = (x - 2) (x - 4) (x + 5) (x - 5 I) x == 0;

Select[Solve[eqn, x], Element[#[[1, 2]], Reals] && #[[1, 2]] > 0 &]

{{x -> 2}, {x -> 4}}

Select[NSolve[eqn, x], Element[#[[1, 2]], Reals] && #[[1, 2]] > 0 &]

{{x -> 2.}, {x -> 4.}}


Bob Hanlon

---- Elements <philyer at gmail.com> wrote: 
> Hi everyone,
>  I'm dealing with an equation with NSolve, and  there are many roots
> of this equation, but I only need the roots which a real and positive.
> So which function or option should I choose?
> Thanks!
> 
> -- 
> Best Wishes!
>  Yours Sincerely
>