Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Roots in negative/positive plane
Replies: 3   Last Post: Dec 18, 2013 2:22 PM

 Messages: [ Previous | Next ]
 Alex Posts: 14 Registered: 12/18/13
Re: Roots in negative/positive plane
Posted: Dec 18, 2013 2:10 PM

"Nasser M. Abbasi" wrote in message <l8sr49\$gog\$2@speranza.aioe.org>...
> On 12/18/2013 12:44 PM, Alex wrote:
> > I have a polynomial and i want to know how many roots are in negative or positive
> >
> > p=[1 5 8 1 5];
> > roots(p)
> > ans =
> >
> > -2.6171 + 1.3412i
> > -2.6171 - 1.3412i
> > 0.1171 + 0.7513i
> > 0.1171 - 0.7513i
> >
> > zplane(p)
> >
> > The plot show that i have 2 roots in negative plane and 2 roots
> >in positive plane. Thank you!
> >

>
> may be you can use real and imag?
>
> p=[1 5 8 1 5];
> r=roots(p)
> length(find(real(r)>0))
> 2
>
> etc...
>

In the example i wrote, yes the roots are in the complex plane. I have an input any polynomial and want to know how many roots are in the negative or positive plane. I understand and thank you!

Date Subject Author
12/18/13 Alex
12/18/13 Nasser Abbasi
12/18/13 Alex
12/18/13 Nasser Abbasi