Polynomials

Let's learn something different today.

We study polynomials at school, so we are going to learn anything about how Scilab works with them.

First, this post is moved to fractions of polynomials, for example*:


For work with polynomials in Scilab, we use the %s as the variable. Look the example**:

-->A = %s^2 + %s + 1
A =

2
1 + s + s

-->B = %s + 2
B =

2 + s

-->R = A*B
R =

2 3
2 + 3s + 3s + s

-->Q = A/B
Q =

2
1 + s + s
---------
2 + s

-->S = A + B
S =

2
3 + 2s + s

-->D = A - B
D =

2
- 1 + s


Observe that Scilab works correctly with the coefficients.

Now, let's work more, if we have a fraction of polynomials and we need just the denominator:

-->Q = (%s + 1)/(%s^2 + 2*%s + 2)
Q =

1 + s
---------
2
2 + 2s + s

-->Dem = denom(Q)
Dem =

2
2 + 2s + s


Following with the example, now we need just the numerator:

-->Num = numer(Q)
Num =

1 + s


And now, we need the roots of the denominator and of the numerator:

-->R_Dem = roots(Dem)
R_Dem =

- 1. + i
- 1. - i

-->R_Num = roots(Num)
R_Num =

- 1.


If anyone has studied linear systems, post a comment here.
If nobody has studied it, you can make a post too.

-----------------------
* I use OpenOffice Math for create the equations.

** The blog doesn't work with white spaces, but Scilab puts the higher coefficients after.