Dymo | Map label placer with simulated annealing | Frontend Framework library

This is a good point and there's no reason we can't add this method, and we should for API consistency.

In the mean time, you can access the parameter_options dictionary after add_parameter to change settings. For instance,

Did you try to use xml-js?

You can edit structure as js objects and then translate it to xml.

For example:

I had similar issues with the dymo connect SDK and winforms. you can tell the app that the system will handle DPI settings, rather than the application. Open properties of the executable -> Compatibility -> Change high DPI settings -> enable override high DPI scaling -> select system

Dymos will integrate any state you give it. In this case, you need to add a state for J and then also compute a state rate for it --- J_dot.

1. In general OpenMDAO You can have vector valued ref/ref0 for design variables. Dymos should, in theory, also support this. You can give a ref/ref0 the same size as your state and then Dymos will extend it out to the full num_nodes size for you. Unfortunately, as of Dymos V 1.30 it looks like this doesn't quite work. We've logged that bug here, and it should be fixed by V1.4.

2. OpenMDAO does not allow mixed units within arrays. This was an intentional design choice related to details about how unit conversions are handled and how to keep them efficient (both in terms of memory and compute usage). Because OpenMDAO doesn't allow it, Dymos can't.

So you either need to split the state up into multiple variables, or work in nondimentional quantities.

1. For parameters and controls this is fairly strait forward via OpenMDAO's APIs. If you want finer grained index control, just set opt=False for all of them. Dymos will expose them as inputs at the top of the phase/trajectory for you (you can use the N2 to find them). Then you can call the native OpenMDAO API add_design_var on those phase/trajectory level inputs with whatever indecies you want.

Doing this for states isn't a great idea. Without getting to far into the math... Dymos works really hard to keep a well defined (in the mathematical sense) optimization problem for you. For states that means carefully matching up the defect constraints with the design variables. You can't just turn off part of a state array without also addressing the corresponding defect constraints. Of course, if you mess with the defect constraints then you aren't getting valid physics any more. This is such a huge can of worms that you really just don't want to touch it.

You're correct that a max function is not differentiable. However, there is a similar function that we provide which is: the KS function

Its not a perfect replacement for a max, but in this context is it very good. You can pass in the entire time series and then it will output a close approximation of the maximum value from that array.

There is a rho option which controls how close to a max function your approximation gets. A larger value is more max-like, but also has poorer numerical conditioning because the derivatives around the max start to get very larger. The default value of 50 is probably fine, but you can experiment with that value if you need to.

DeviceCapabilities() returns a signed int, not an unsigned DWORD.

The unsigned value 4294967295 is hex 0xFFFFFFFF, which is the same numeric value as a signed -1.

Per the DeviceCapabilities() documentation:

Return value

If the function succeeds, the return value depends on the setting of the fwCapability parameter. A return value of zero generally indicates that, while the function completed successfully, there was some type of failure, such as a capability that is not supported. For more details, see the descriptions for the fwCapability values.

If the function returns -1, this may mean either that the capability is not supported or there was a general function failure.

You are not accounting for the possibility of DeviceCapabilities() failing (or PrintDlgEx(), either).

Try this:

As of Dymos 1.1.0, and August 2021, time-stepping integration is not included. As you pointed out solve_segments provides very similar functionality. We are working on time-stepping, initially with fixed-step Euler integration. We plan to extend it to higher-order RK methods and adaptive-step. It will allow the same control transcriptions we already have (segment-by-segment interpolation of fully dynamic controls, and phase-wide interpolation of polynomial controls).

We not ready to announce a timeline for when this will be available though. It's still a bit early in development. A safe bet would be about 1 year before the feature is fully baked though.

You didn't provide the code to your MatrixMatrixProductComp, but I can make an educated guess as to whats going on because you referenced the MatrixVectorProductComp in OpenMDAO's standard library.

For all components in OpenMDAO's standard library, the developers have already implemented and verified the derivatives. Thus, there is no need to have those components show up in the output of check_partials for 99.9999% of the time. It would just clutter up the output that users need to see.

There is a hidden, undocumented, flag _no_check_partials that gets turned on in these components so that check_partials skips them. Now that I have blabbed about this hidden flag all over the internet :) ... here is where its assigned in the MatrixVectorProductComp The Dymos library used this feature too, so that Dymos components didn't clutter up user check_partials outputs for their ODE components and groups.

Again, Dymos did this because those partials have already been carefully verified! Also there is special code in Dymos that flips that flag off so that internal tests can verify Dymos component partials.

Most likely you just need to set that attribute to False, and you'll get some check_partials output you can use in a test. I am being careful to emphasize that this flag should only be used with great caution. Bad partials will break an optimization, and if you have that flag turned on then you may simply never get a report of that component in check_partials.

In your case, you got burned by having no other components in your model, so you got the empty dictionary error. Generally, I do not recommend any user code use this flag at all.