zbrent: Van Wijngaarden-Decker-Brent Root-finding Algorithm

In kmconfband: Kaplan-Meier Simultaneous Confidence Band for the Survivor Function

Description

The function zbrent searches the interval int for a root, i.e., a zero, with respect to the first argument of a one-dimensional user-supplied function func.

Usage

   zbrent(func,int,tol)

Arguments

func	the function for which the root is sought
int	a vector representing the interval in which the required root is located
tol	the desired accuracy (convergence tolerance)

Details

The values of func at the two endpoints of int must have opposite signs.

Value

The algorithm returns the required root unless there is none, or the algorithm exceeds 100 iterations. In the latter case, an error message is displayed, and the current approximation is returned.

Author(s)

David E. Matthews [e-mail]

References

Press W.H., Flannery B.P., Teukolsky S.A., Vetterling W.T. (1988) Numerical Recipes: The Art of Scientific Computing. Cambridge: Cambridge University Press.

See Also

confband, exact

Examples

f<-function(x) x*(x^2-1)+0.5
x<-seq(-2,2,length=100)
plot(x,f(x),type="l")
zbrent(f,c(-2,2),1.0e-10)

Example output

Loading required package: survival
[1] -1.191488

kmconfband documentation built on May 2, 2019, 2:49 p.m.