# Polar Diagram

Started by November 28, 2009
```Hi to all!

I'm studing Nyquist plot for assessing the stability of a system with
feedback.

I'd like to calculate point where the graph intersect Real and Imaginary
axis.
I've found a method witch is based on Routh table, using it it's possible to
find the point of intesect.

Does anyone know where I can find somo information about?

Thaink you very much!
David

```
```On Nov 28, 4:34&#2013266080;pm, "David" <s...@spam.com> wrote:
> Hi to all!
>
> I'm studing Nyquist plot for assessing the stability of a system with
> feedback.
>
> I'd like to calculate point where the graph intersect Real and Imaginary
> axis.
> I've found a method witch is based on Routh table, using it it's possible to
> find the point of intesect.
>
> Does anyone know where I can find somo information about?
>
> Thaink you very much!
> David

Wikipedia
```
```John,

>> Wikipedia

discussed this. thank you very much!

Bye
David

```
```>Hi to all!
>
>I'm studing Nyquist plot for assessing the stability of a system with
>feedback.
>
>I'd like to calculate point where the graph intersect Real and Imaginary

>axis.
>I've found a method witch is based on Routh table, using it it's possible
to
>find the point of intesect.

Why do you care where the Nyquist plot itself intersects the axes?  Are
you confusing it with a root locus plot (or something else)?  Are you
trying to draw the plot by hand (I've not seen 'rules of thumb' for doing
this, but it sounds doable), rather than use it?

```