Dear all, As a part of a program I am developing in Julia, I would like to have boundary conditions defined as Julia functions. However, I ran into the “too new for this world problem”. It took me quite a while to come up with MWE. (It may still be a bit on the big side, but anything smaller sim…

I think, it would be better to parse those boundary conditions as variables (probably arrays?) instead of baking them into hard code. You can still execute those functions but then you have to use Base.invokelatest.

What you see is called world age problem which also hit me before. The question is: Why do you need Meta.parse? I mean, you can define your function like always and just pass it as a variable?

Well, no. In reality the stag_allocate reads boundary conditions from a file and parses them into Julia functions. (I know this is not a good practice because it is anywhere from unsafe to downright dangerous, but I think it is easier for future users to change one line in a separate input file th…

I was trying with Base.invokelatets but it didn’t lead me anywhere, really. The same error would still appear, but precisely at the call to Base.invokelatets. (Maybe I was doing something wrong.) Arrays would work for steady boundary conditions, but very often they are time-dependent, so one has …

julia> function wa() g = eval(Meta.parse("(x, y) -> x^2 + y^2")) Base.invokelatest(g, 1, 2) end wa (generic function with 1 method) julia> wa() 5 julia> function wa() g = eval(Meta.parse("(x, y) -> x^2 + y^2")) g(1,2) end wa (generic functi…

Yes, bet recreating new source code is even worse? Each time, you would have an additional compilation lag. If those numbers are passed as parameters, you compile only once.

Well, that’s not the way I understand Julia works. You read boundary conditions once, compile functions describing boundary conditions also once, and for the rest of the simulation you use compiled code. Maybe I am missing something here?

[image] Niceno: Arrays would work for steady boundary conditions, but very often they are time-dependent, so one has to recompute them at the beginning of each time step. That confuses me? Why do arrays not work but generated functions do?

Here is a typical example: 28.4*(0.25-(y^2))*(0.25-(z^2))*(1.0-exp(-τ)) Inlet velocity depends on y and z coordinates and time. Arrays holding values at boundaries would take you only so far since you have to recompute them at ever time step anyhow. Such equations I would like to parse into Juli…

Why doesn’t function(y, z, τ, arr) arr[1]*(arr[2]-(y^2))*(arr[3]-(z^2))*(arr[4]-exp(-τ)) end work?

Because I am trying to make it as user input. The code is not just for me to run, and not just for one case to solve. Another example may involve sine, cosine functions, the functions change if the geometry moves and so forth.

Too new for this world problem when called from a function

General Usage

roflmaostc November 2, 2021, 6:45pm 14

The topic was also discussed here before.

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Too new for this world problem when called from a function

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