OpenMx Developer Forums

I implemented the square bracket operator for MxAlgebra expressions. In an algebra it is now possible to write A[x, y] or A[,y] or A[x,] or A[,]. x and y must be either numeric literal values, or they can also be an arbitrary 1 x 1 matrices if you want to get fancy. A lion's share of the credit should be attributed to Tim Brick. The matrix operator and function interface that we designed made it fairly easy to implement this operator. It seemed like the square-bracket operator might be useful. See models/passing/AlgebraComputePassing.R for some examples.

I seem to have this almost working but for a pesky error:

Error: The job for model 'twinACE' exited abnormally with the error message: Objective returned invalid value.
Execution halted

Script and data files attached (albeit with an extra _ in the name of the latter, ffs).

We spoke at the developer's meeting about reserved symbols for labels. The symbols that cannot be used are "." which is special as a separator between the model name and label name. Also the '[' and ']' are special and they are used for substitutions. Also it turns out that if you give a model an empty name "", things currently break. I'll probably throw an error if you try to name anything with the empty name.

The deveoper's meeting began with some talk of migrating the web server and subversion repository to a mac mini server. Some logistical issues regarding this issue were discussed. The next topic of conversation was designing an interface for the likelihood variables in a FIML objective function.

Hi folks, I am just pasting in here some email discussion between Greg Carey and myself concerning the language interface. In the thread we drifted off to talk about models of assortative mating.

Greg Carey's email:

mike,
just looked at openMx and am worried that things might get unnecessarily complicated when dealing with large multivariate problems.

One of the nice things about John Fox's sem package is that it can output path diagrams. I think this is a very nice feature, and would love to see it in OpenMx. Even better if it's implemented using grid or some other R graphics system instead of graphviz (as the sem package does). Graphviz works great once you get it installed and set up, but this can be difficult.

I was bugging you about R usage last month.  I think some elements in your design are going to confuse experienced R users and from your Wiki I gather they befuddle the new users as well. Some things you can addressed by making your "tutorial go slower". But you could tighten up usage instead, and avoid the confustion in the start.