# rootwrap: zeroin: Find a single root of a function of one variable... In rootoned: Roots of one-dimensional functions in R-only code

## Description

Find a single root of a function of one variable within a specified interval. Brent's method.

## Usage

 ```1 2``` ``` rootwrap(fn=fn, gr=NULL, ri=NULL, method="uniroot", ftrace=TRUE, ...) rwx(fn=fn, gr=NULL, ri=NULL, method="uniroot", ftrace=TRUE, ...) ```

## Arguments

 `fn` A real function of a single variable for which a root is desired. `gr` A real function of a single variable giving the gradient (derivative) of `fn`. `ri` A vector of two real numbers defining the ends of the interval in which to search. `method` A character string giving the name of the rootfinding method to be used. Must be one of the methods `rootwrap` supports. See the source code. `ftrace` If TRUE, provided diagnostic output of the process of rootfinding. `...` Extra data needed to compute the function `f`.

## Details

This routine is a wrapper to allow a consistent calling sequence for a number of different rootfiners.

## Value

The output is a list consisting of

• root The estimate, b, of the position of the root.

• froot The value of the function at this point, f(b).

• rtol The width of the interval in which the root exists.

• iter The number of iteration cycles used.

## References

Nash, John C. (1979) Compact numerical methods: linear algebra and function minimisation. Bristol UK: Adam Hilger.

## See Also

`optimize`

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10``` ```# Dekker example # require(rootoned) # phi <- 6 dek <- function(x, phi=0){ 1/(x-3) - phi } # r1 <- rootwrap(dek, ri=c(3.0000001, 6), ftrace=TRUE, method="uniroot", phi=6) r1 <- rwx(dek, ri=c(3.0000001, 6), ftrace=TRUE, method="uniroot", phi=6) r1 # r2 <- rootwrap(dek, ri=c(3.0000001, 6), ftrace=TRUE, method="root1d", phi=6) r2 <- rwx(dek, ri=c(3.0000001, 6), ftrace=TRUE, method="root1d", phi=6) r2 ```

rootoned documentation built on Aug. 29, 2018, 3 a.m.