backSpline
Monotone Inverse Spline

### Description

Creates a monotone inverse Spline.

### Usage

    backSpline(object)
    ## S3 method for class 'nbSpline':
    backSpline(object)
    ## S3 method for class 'npolySpline':
    backSpline(object)

### Arguments

object | a spline object inheriting from class npolySpline or nbSpline (typically produced by interpSpline). The spline must be monotone.

Value
returns an object of class c("polySpline", "spline") that contains the following two components:

- "knots"
- "coefficients"

The returned object represents a monotone spline that approximates the inverse function of the input spline. The first derivatives at its knots are initially set to be the reciprocals of the first derivatives of the input spline at its knots. Hyman's algorithm is used to alter any of those derivatives that would cause the spline to be non-monotone.
Differences between Spotfire Enterprise Runtime for R and Open-source R
In open-source R, backSpline uses a different algorithm, (usually) resulting in a slightly different splines.
See Also
interpSpline.
Examples

    isp <- interpSpline(c(1,2,3,4),c(5,9,11,12))
    predict(backSpline(isp))

Package splines version 6.1.5-18
Package Index