derivatives: First and Second Derivatives

In irtProb: Utilities and Probability Distributions Related to Multidimensional Person Item Response Models

Description

Three points first and second derivatives numerical approximation used with the m4plEstimateMore function.

Usage

 fprime( x, FUN = "FP", h = 0.001, names = paste("x", c(1:length(x)),
 sep = ""))
 fsecond(x, FUN = "FP", h = 0.001, names = paste("x", c(1:length(x)),
 sep = ""))
 

Arguments

x	numeric; vector of values at which the derivation is to be done.
FUN	function; function to derive.
h	numeric; neighbouring value.
names	character; names given to each results. DEFAULT to the existing names of the vector x.

Details

This function could be used for numerical derivation in general, but is dedicated to be used internally by m4plEstimateMore. For other general purposes D, deriv and deriv3 are preferred.

Value

fprime	numeric; vector of first derivatives.
fsecond	numeric; matrix of second derivatives.

Author(s)

Gilles Raiche, Universite du Quebec a Montreal (UQAM),

Departement d'education et pedagogie

[e-mail], http://www.er.uqam.ca/nobel/r17165/

References

Press, W. H., Vetterling, W. T., Teukolsky, S. A. and Flannery, B. P. (2002). Numerical recipees in C++. The art of scientific computing, 2nd edition. Cambridge, United Kingdom: Cambridge University press.

Yakowitz, S. and Szidarovszky, F. (1986). An introduction to numerical computations. New York, New Jersey: MacMilla.

See Also

D, deriv and deriv3

Examples

## .....................................
 test  <- function(x) 2*x+5
  test(   x=0)
  fprime( x=0, FUN=test)
  fsecond(x=0, FUN=test)
## .....................................
 test2 <- function(x) 2*(x[1]*x[2])+5
  test2(  x=c(0,0))
  fprime( x=c(0,0), FUN=test2)
  fsecond(x=c(0,0), FUN=test2)
 

irtProb documentation built on May 2, 2019, 1:30 p.m.