ModelingToolkit -- news?

[baggepinnen]

@BLI

Constructor ODESystem now requires the independent variable as second argument [e.g., ODESystem(eqs,t) – in the past, the constructor tried to infer the independent variable, i.e., ODESystem(eqs) would often work]. Is this correct?

correct

@BLI

Field (and function) states of systems has been changed to unknowns?

correct

@BLI

Does this mean that now, ModelingToolkit has built-in names for the time variable (t_nounits) and time differentiation (D_nounits)? And that the examples choose t and D, respectively, as aliases for t_nounits and D_nounits?

correct

@BLI

I assume that the purpose of this is to (i) avoid having to define these when using MTK

correct

@BLI

and possibly getting more efficient code

not really

@BLI

that the user can choose her/his own aliases

you can, but you could that before as well

@BLI

make sure that all libraries use the same name for the time variable [t_nounits].

the symbolic name of the time variable is t, it’s the julia variable that is called t_nounits

julia> ModelingToolkit.t_nounits
t

@BLI

The “casual user” can still define time as @variables t and differentiation as D = Differial(t), but then this code will not work in conjunction with, e.g., ModelingToolkitStandardLibrary. Right?

I think it would work anyway, but there is no need to define these yourself anymore