问题描述:

Im trying to plot the roots of a polynomial, and i just cant get it.

First i create my polynomial

`p5 = [1 0 0 0 0 -1] %x^5 - 1`

r5 = roots(p5)

stem (p5)

Im using the `stem`

function, but I would like to remove the stems, and just get the circle around the roots.

Is this possible, is stem the right command?

Thanks in advance,

PS: This is not homework, but very close, will tag it if requested.

If you have complex roots that you want to plot with the real part on the x-axis and the imaginary part on the y-axis, you can just use the PLOT function:

```
plot(r5,'o');
```

If you are wanting to plot the function *and* the roots together, you will have to ignore the complex roots (as yuk mentions in the comment below):

```
p5 = [1 0 0 0 0 -1];
r5 = roots(p5);
realRoots = r5(isreal(r5)); %# Gets just the real roots
x = -2:0.01:2; %# x values for the plot
plot(x,polyval(p5,x)); %# Evaluate the polynomial and plot it
hold on; %# Add to the existing plot
plot(realRoots,zeros(size(realRoots)),'o'); %# Plot circles for the roots
```