R Functions and User Interface

Hi

Anyone have any idea what this error message means?

Error in single.na(to) : argument is missing, with no default
Calls: mxModel -> mxPath -> generatePath -> single.na
Execution halted

I hesitate to post the script, 308 lines at present...

I am using the term "labeled fixed value" to refer to a (row, col) entry in a MxMatrix object where free = FALSE and label is not a NA value. They have not generated much discussion so far. The only restriction we have is that a free parameter in the model cannot have the same name as a labeled fixed value. Here are some additional ideas:

• Labeled fixed values can be used inside an MxAlgebra expression just as we are going to allow free parameters inside an MxAlgebra expression.

There has been some talk recently of simplifying the MxAlgebra interface in two regards. It would be convenient to specify constant values or matrices in an MxAlgebra statement, without having to explicitly declare a separate MxMatrix that contains constant values. It would also be convenient to specify free parameters in an MxAlgebra statment, without having to explicitly declare a separate 1 x 1 MxMatrix that contains the free parameter. We have been referring to these proposed changes as constant substitution and free parameter substitution, respectively.

If 'compute' is FALSE (the default), then MxAlgebra expressions returns their current value as they have been computed by the optimization call (using mxRun). If the 'compute' argument is TRUE, then MxAlgebra expressions will be calculated in R. Any references to an objective function that has not yet been calculated will return a 1 x 1 matrix with a value of NA. Users will like this feature because it allows them to compare the result of algebraic expressions as computed by the back-end against those values computed by R.