# brentdekker: Brent-Dekker Root Finding Algorithm In pracma: Practical Numerical Math Functions

 brentDekker R Documentation

## Brent-Dekker Root Finding Algorithm

### Description

Find root of continuous function of one variable.

### Usage

``````brentDekker(fun, a, b, maxiter = 500, tol = 1e-12, ...)
brent(fun, a, b, maxiter = 500, tol = 1e-12, ...)
``````

### Arguments

 `fun` function whose root is to be found. `a, b` left and right end points of an interval; function values need to be of different sign at the endpoints. `maxiter` maximum number of iterations. `tol` relative tolerance. `...` additional arguments to be passed to the function.

### Details

`brentDekker` implements a version of the Brent-Dekker algorithm, a well known root finding algorithms for real, univariate, continuous functions. The Brent-Dekker approach is a clever combination of secant and bisection with quadratic interpolation.

`brent` is simply an alias for `brentDekker`.

### Value

`brent` returns a list with

 `root` location of the root. `f.root` funtion value at the root. `f.calls` number of function calls. `estim.prec` estimated relative precision.

### References

Quarteroni, A., R. Sacco, and F. Saleri (2007). Numerical Mathematics. Second Edition, Springer-Verlag, Berlin Heidelberg.

`ridders`, `newtonRaphson`

### Examples

``````# Legendre polynomial of degree 5
lp5 <- c(63, 0, -70, 0, 15, 0)/8
f <- function(x) polyval(lp5, x)
brent(f, 0.6, 1)                # 0.9061798459 correct to 12 places
``````

pracma documentation built on Nov. 10, 2023, 1:14 a.m.