R: A reorganization of the call to numDeriv grad() function.

grnd {optextras} | R Documentation

## A reorganization of the call to numDeriv grad() function.

### Description

Provides a wrapper for the numDeriv approximation to the gradient of a user supplied objective function `userfn`.

### Usage

           grnd(par, userfn, ...)

### Arguments

`par` | A vector of parameters to the user-supplied function `fn`
`userfn` | A user-supplied function
`...` | Other data needed to evaluate the user function.

### Details

The Richardson method is used in this routine.

### Value

`grnd` returns an approximation to the gradient of the function userfn

### Examples

    cat("Example of use of grnd\n")
    require(numDeriv)
    myfn<-function(xx, shift=100){
        ii<-1:length(xx)
        result<-shift+sum(xx^ii)
    }
    xx<-c(1,2,3,4)
    ii<-1:length(xx)
    print(xx)
    gn<-grnd(xx,myfn, shift=0)
    print(gn)
    ga<-ii*xx^(ii-1)
    cat("compare to\n")
    print(ga)

[Package optextras version 2016-8.8 Index]