polyroot {base} R Documentation

## Find Zeros of a Real or Complex Polynomial

### Description

Find zeros of a real or complex polynomial.

### Usage

```polyroot(z)
```

### Arguments

 `z` the vector of polynomial coefficients in increasing order.

### Details

A polynomial of degree n - 1,

p(x) = z1 + z2 * x + ... + z[n] * x^(n-1)

is given by its coefficient vector `z[1:n]`. `polyroot` returns the n-1 complex zeros of p(x) using the Jenkins-Traub algorithm.

If the coefficient vector `z` has zeroes for the highest powers, these are discarded.

### Value

A complex vector of length n - 1, where n is the position of the largest non-zero element of `z`.

### References

Jenkins and Traub (1972) TOMS Algorithm 419. Comm. ACM, 15, 97–99.

### See Also

`uniroot` for numerical root finding of arbitrary functions; `complex` and the `zero` example in the demos directory.

### Examples

```polyroot(c(1, 2, 1))
round(polyroot(choose(8, 0:8)), 11) # guess what!
for (n1 in 1:4) print(polyroot(1:n1), digits = 4)
polyroot(c(1, 2, 1, 0, 0)) # same as the first
```

[Package base version 2.5.0 Index]