nroots: Finding the Number of Roots

In ppham27/setsim: Software tool for the visualization of confidence regions in statistical models

Description

This function finds the number of roots for a given numeric function in a specified domain. It returns the number of roots, positions of the roots and two corresponding intervals containing each root and corresponding function value, respectively. A finer domain discretization will result in more accurate intervals for both a root and corresponding function value. If the user defined function does not intersect x axis, 0 root will be returned.

Usage

nroots(fn, x)

Arguments

fn	a numeric function defined by the user. An object which is not a numeric function will not be allowed.
x	a numeric vector indicating the domain of the numeric function.

Value

n	the number of roots in the domain.
position	the position of the root in the domain. The position will change if a different domain is specified.
range	two intervals containing the roots and corresponding values of the functions evaluated at those roots. x.lower and x.upper indicates the lower end point and upper end point of the interval on x axis that contains a root. y.lower and y.upper indicates the lower end point and upper end point of the interval on y axis that contains the value of the function evaluated at a root.

Examples

x <- seq(-3*pi,3*pi,length=50)
y <- function(x){sin(x)}
nroots(y,x)

a <- seq(10,50,length=30)
fun <- function(a){log(a)}
nroots(fun,a)

ppham27/setsim documentation built on May 25, 2019, 11:25 a.m.