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 2.2.1

Index]