Revision of mxalgebra-help from Fri, 07/09/2010 - 06:09

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Usage

mxAlgebra(expression, name = NA, dimnames = NA)
mxAlgebra() allows you create algebraic expressions based on one or more MxMatrix objects.
Legal functions within an algebra are described here.

    A <- mxMatrix("Full", nrow = 3, ncol = 3, values=1:9, name = "A")
    B <- mxAlgebra(A, name = "B")
    C <- mxAlgebra(A + B, name = "C")
    D <- mxAlgebra(sin(C), name = "D")

    model <- mxModel("AlgebraExample", A, B, C, D )
    fit   <- mxRun(model)

    mxEval(AlgebraExample.D, fit)
    #           [,1]       [,2]       [,3]
    # [1,]  0.9092974  0.9893582  0.9906074
    # [2,] -0.7568025 -0.5440211 -0.2879033
    # [3,] -0.2794155 -0.5365729 -0.7509872

Gotchas

A common misunderstanding is to call mxAlgebra() expecting it to be evaluated without subsequently being placed in a model and run as above. To evaluate an MxAlgebra, it must be placed in an MxModel (along with all referenced MxMatrix objects) and run.

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