DEPRECATED: Create MxAlgebraObjective Object
WARNING: Objective functions have been deprecated as of OpenMx 2.0.
Please use MxFitFunctionAlgebra() instead. As a temporary workaround, MxAlgebraObjective returns a list containing a NULL MxExpectation object and an MxFitFunctionAlgebra object.
All occurrences of
mxAlgebraObjective(algebra, numObs = NA, numStats = NA)
Should be changed to
mxFitFunctionAlgebra(algebra, numObs = NA, numStats = NA)
NOTE: THIS DESCRIPTION IS DEPRECATED. Please change to using mxFitFunctionAlgebra as shown in the example below.
Fit functions are functions for which free parameter values are chosen such that the value of the objective function is minimized. While the other fit functions in OpenMx require an expectation function for the model, the mxAlgebraObjective function uses the referenced MxAlgebra or MxMatrix object as the function to be minimized.
If a model's primary objective function is a mxAlgebraObjective objective function, then the referenced algebra in the objective function must return a 1 x 1 matrix (when using OpenMx's default optimizer). There is no restriction on the dimensions of an objective function that is not the primary, or ‘topmost’, objective function.
To evaluate an algebra objective function, place the following objects in a MxModel object: a MxAlgebraObjective, MxAlgebra and MxMatrix entities referenced by the MxAlgebraObjective, and optional MxBounds and MxConstraint entities. This model may then be evaluated using the mxRun function. The results of the optimization may be obtained using the mxEval function on the name of the MxAlgebra, after the model has been run.
The OpenMx User's guide can be found at http://openmx.ssri.psu.edu/documentation.
# Create and fit a very simple model that adds two numbers using mxFitFunctionAlgebra
library(OpenMx)
# Create a matrix 'A' with no free parameters
A <- mxMatrix('Full', nrow = 1, ncol = 1, values = 1, name = 'A')
# Create an algebra 'B', which defines the expression A + A
B <- mxAlgebra(A + A, name = 'B')
# Define the objective function for algebra 'B'
objective <- mxFitFunctionAlgebra('B')
# Place the algebra, its associated matrix and
# its objective function in a model
tmpModel <- mxModel(model="Addition", A, B, objective)
# Evalulate the algebra
tmpModelOut <- mxRun(tmpModel)
# View the results
tmpModelOut$output$minimumPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.