RMKirkpatrick

> Providing the user with a compute plan that could be revised is nice. Don't forget about `omxDefaultComputePlan()`.

Yes. There is a specific error message OpenMx gives if one of the thresholds it needs to use is `NA`.

@mcneale Correct. And in that case, OpenMx will give the "I hit NA values after only 0 thresholds" error.

> Ok, so NAs work as directly specified elements, but they don't work if an algebra is being used. You know what? Maybe at one point, `NA`s _did_ work if...

Is this resolved? Has anyone appropriately updated the User Guide so that it no longer recommends a broken way to set up thresholds?

I guess I do have _a little_ experience writing code that reads pedigree files into R. See function `FSV.frompedi()` here: https://cran.r-project.org/web/packages/RFGLS/RFGLS.pdf . What would be _really_ slick, of course, is...

I think one could be adapted from the multilevel practical.

@tbates I'm not sure what you mean here: > In OpenMx, mxPath("latent1", to = "latent1", arrows=1) has to be legal. The only way to check that would be to add...

There could be a check at runtime to see if there are any free parameters on the diagonal of the 'A' matrix. Are there any cases where such a thing...

@SteveBoker Interesting. I guess we have to allow free parameters on the diagonal of 'A'.