bisect: Bisection Method
In zhicongz/AnomDetct: Anomaly Detection via Scan Statistics

Description Usage Arguments Details Value Author(s) Examples

This function returns the results of binary searching on a monotone increasing function fn.

1	bisect(fn, lower, upper, discrete = TRUE, target, right = TRUE,index = TRUE,...)

`fn`	a monotone increasing function with numeric/character/logical output. If output is character, the increasing defines as alphabetical order; if it is logical, the increasing defines as order from 'FALSE' to 'TRUE'.
`lower`	lower bound of the function `fn` domain.
`upper`	upper bound of the function `fn` domain.
`discrete`	logical; if 'TRUE', the domain is discrete; otherwise, the domain is continuous
`target`	the target needs to be searched in the range of `fn`.
`right`	logical; if 'TRUE', search for the smallest value (right limit for continous domain) of 'x' in the domain of `fn` such that fn(x) >= target; otherwise, search for the largest value (left limit for continous domain) of 'x' in the domain of `fn` such that such that fn(x) <= target.
`index`	logical; if 'TRUE', returns the input value of the `fn` satisfied the searching condition; otherwise, returns the output value of `fn` instead.
`...`	further arguments, see `Details`

Here are more arguments that are provided by this function:

unit: If the domain is discrete, unit can be used for specified the step length. Default value is '1'.
tol: If the function fn is continous, tol is used for error tolerance. Default value is '10^(-7)'.

For the case one want to apply binary search on a given vector 'arr', a simple way is define:

fn <- function(x) arr[x]

and search on discrete domain c(1,length(arr)) with unit = 1.

If index is 'TRUE', returns a number represents the searching results on domain of fn; else, returns the searching results on range of fn.

Zhicong Zhao

fn <- function(x) if(x>3 && x<5) 4 else x
bisect(fn,0,10,discrete = F,target = 4,right = T) # returns 3 because right limit of f(3) = 4
bisect(fn,0,10,discrete = F,target = 4,right = F) # returns 5 because left limit of f(5) = 4
bisect(fn,0,10,discrete = T,target = 4,right = T) # returns 4 for discrete domain