Scilab Home page | Wiki | Bug tracker | Forge | Mailing list archives | ATOMS | File exchange
Change language to: Français - Português - 日本語 - Русский

Scilab Help >> Polynomials > poly

# poly

polynomial definition

### Syntax

`p = poly(a, vname, ["flag"])`

### Arguments

a

a matrix or real number

vname

a string, the symbolic variable name. The string must be 4 characters max.

"flag"

string (`"roots"`, `"coeff"`), default value is `"roots"`.

Shortcuts can be also used: `"r"` for `"roots"` and `"c"` for `"coeff"`.

### Description

If `a` is a matrix,

`p` is the characteristic polynomial i.e. `determinant(x*eye()-a)`, `x` being the symbolic variable.

If `v` is a vector,
• `poly(v,"x",["roots"])` is the polynomial with `roots` the entries of `v` and `"x"` as formal variable. (In this case, `roots` and `poly` are inverse functions).

 Note that Infinite roots gives zero highest degree coefficients.

• `poly(v,"x","coeff")` creates the polynomial with symbol `"x"` and with coefficients the entries of `v` (`v(1)` is the constant term of the polynomial). (Here `poly` and `coeff` are inverse functions).

`s=poly(0,"s")` is the seed for defining polynomials with symbol `"s"`.

### Examples

```s=poly(0,"s");
p=1+s+2*s^2
A=rand(2,2);
poly(A,"x")
//rational fractions
h=(1+2*%s)/poly(1:4,'s','coeff')```

• coeff — coefficients of matrix polynomial
• roots — roots of polynomials
• varn — symbolic variable of a polynomial or a rational
• horner — polynomial/rational evaluation
• derivat — Rational matrix derivative
• matrices — Scilab objects, matrices in Scilab
• rational — Scilab objects, rational in Scilab

### History

 Version Description 5.5.0 The only values allowed for the third argument are "roots", "coeff", "c" and "r".