inverseFunction: Inverse Function

In mathphysmx/inverseFunction: Numerical inverse of a univariate function

Description

Computes the numerical inverse of a univariate function

Only computes a sigle inverse. For multiple inverseses, use a (for, while) loop.

Usage

inverseFunction(dvar, fun, interval = c(0, 1), silent = TRUE, ...)

Arguments

dvar	scalar value. dependent variable, usually writen the cartesian plane as 'y'.
fun	A list of parameters (name included as fun) describing a function.
interval	a vector containing the end-points of the interval to be searched for the root.
silent	logical: should the report of error messages be suppressed?
...	further arguments passed to statsuniroot.

Examples

myFun <- function(x, b=3) return(2*x+b)
fe <- list(fun='myFun', b = 4)
# dvar = y = 10 = 2*3 + 4
inverseFunction(dvar = 10, fun = fe, interval = c(-10, 10), silent = TRUE)

# Example 2:
fe <- list(fun = 'pnorm', mean = 3, sd = 2)
# pnorm(4.7, mean = 3, sd = 2) = 0.8023375
inverseFunction(dvar = 0.8023375, fun = fe, interval = c(4, 5), silent = TRUE)

# Example 3:
exy <- cbind(1:5, c(2, 4, 3, 6, 7)); print(exy)
set.seed(1); exy <- exy[sample(1:5), ]
library(bernstein)
library(empiricalDistribution)
empCopulaCountsmatrix <- forwardDifference(empiricalCDF2Dcounts(exy))
eu <- 0.3; ev <- 0.8
et <- bernstein2DderivativeX(v = ev, u = eu, diffEC = empCopulaCountsmatrix)
efun <- list(fun = 'bernstein2DderivativeX', u = eu,
            diffEC = empCopulaCountsmatrix)
inverseFunction(dvar = et, fun = efun)

mathphysmx/inverseFunction documentation built on May 7, 2019, 10:55 p.m.