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As someone who has no idea what this is about bar the landing page explanation, and isn't in this space -- it would be great if the front page had examples, or

As someone who has no idea what this is about bar the landing page explanation, and isn't in this space -- it would be great if the front page had examples, or links to examples. 30 seconds of clicking around and I've failed to find sth compelling.

Cthulhu_ 2y ago
It apparently sells merchandising for their own brand though.
- michaeltiller 2y ago
  The Modelica Association is a non-profit that publishes the specification, the standard library and all conference proceedings for free. We sell merch in part because people in the Modelica community like the language and like to show it but also as a way to fund the not for profit activities.
- jrowen 2y ago
  Downvoted but relevant...nothing says corporate bullshit like a niche programming language with logos and merch featured far more prominently than examples or explanation...
  - michaeltiller 2y ago
    Just to be clear, there is absolutely nothing "corporate" about that web site. It is a non-profit organization.
    - jrowen 2y ago
      Sorry, I guess that was rude, I don't know anything about it, just a snap judgment of the landing page.
PittleyDunkin 2y ago
Modelica Language -> Modelica By Example -> https://mbe.modelica.university/ https://mbe.modelica.university/ Took me under 5 seconds to find.
- observationist 2y ago
  [flagged]
  - alwa 2y ago
    I wonder if some of those words might be terms-of-art, written with a specialist rather than a generalist audience in mind.
  - porcoda 2y ago
    Accessible to whom? I work in a field that uses things like Modelica and it reads just fine to me.
bglazer 2y ago
Here are some examples. Looks like a simplified framework for writing physical and electrical system simulations. https://mbe.modelica.university/ https://mbe.modelica.university/
- spookie 2y ago
  I wouldn't say simplified. You can model a lot of systems with it. It's pretty good.
- michaeltiller 2y ago
  Over 20 years ago I modeled an internal combustion engine, an automatic transmission and a multibody chassis model all in a single model. IIRC, the model had something like 250,000 equations in it and it modeled combustion, hydraulics, friction, and 3D rigid body motion. It is capable of far more than simple models. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=2234d4c76767d2609df20bfff4a31b7e794d4531 https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...
  - bobim 2y ago
    Ah! You're the author of Modelica by example?
    - michaeltiller 2y ago
      Yes. And "Introduction to Physical Modeling with Modelica". I also built the Modelica Playground (which I deliberately didn't link to because a thundering herd of HN readers would have crashed it).
      - bobim 2y ago
        Nice to cross your path, I got the first one to kickstart myself some years ago (and still struggling with evaporation / condensation). Would you recommend the second to introduce a colleague to OpenModelica? He is into gPROMS but will lose access to the software at retirement. Sidenote: invest in software with freedom to operate and good knowledge reusability.
nativeit 2y ago
The first link for “Modelica Language” includes tutorials and examples. Five seconds of clicking around got me to: > Let us consider an extremely simple differential equation: x = (1-X) Looking at this equation, we see there is only one variable, x This equation can be represented in Modelica as follows: model FirstOrder Real x; equation der(x) = 1-x; end FirstOrder; This code starts with the keyword model which is used to indicate the start of the model definition. The model keyword is followed by the model name, FirstOrder. This, in turn, is followed by a declaration of all the variables we are interested in. [et cetera]
qart 2y ago
As someone who is a curious outsider to Modelica, it piqued my interest a few years ago when I found out that this language lets you write equations more directly than most other programming languages. Take the ideal gas law, for example, PV = nRT, which has 5 identifiers. In most programming languages, you'd have to keep only one variable to the left, that is assigned to, e.g. T=PV/nR, and a similar set of equations if you want to determine any of the other variables, given the rest. In Modelica, the same equation, expressed as you would in natural math, works for determining the unknown, based on the knowns. https://mbe.modelica.university/behavior/equations/electrical/ https://mbe.modelica.university/behavior/equations/electrica... I don't know much beyond this.
- alhirzel 2y ago
  This is generally referred to as an acausal modeling environment - you don't need to bring the causality of mathematical relationships, just bring the relationships. There are several other tools in this space, not the least prevalent of which is Mathworks' Simscape product line [1]. Wolfram has a solution that is also very similar to Modelica [2]. Finally, I believe that you will find ModelingToolkit.jl [3] worth a look (along with Julia in general) if your interest is piqued here by Modelica. I believe MTK is a big slice of the future of acausal modeling tools. [1] https://www.mathworks.com/products/simscape.html https://www.mathworks.com/products/simscape.html [2] https://www.wolfram.com/system-modeler/ https://www.wolfram.com/system-modeler/ [3] https://docs.sciml.ai/ModelingToolkit/stable/examples/spring_mass/ https://docs.sciml.ai/ModelingToolkit/stable/examples/spring...
  - buescher 2y ago
    Wolfram SystemModeler is a Modelica implementation.
JKCalhoun 2y ago
I wonder if anyone is keeping a list of the new languages that come out every year.
- michaeltiller 2y ago
  Modelica is nearly 30 years old, BTW.
  - JKCalhoun 2y ago
    TIL. Thanks.
pixelpoet 2y ago
Another day, another nondescript product name on HN for Russian roulette clicking. Dare to say anything about it, get downvoted into a smoking hole in the ground (e.g. by webdevs who assume everyone else is), yadda yadda... I'm pretty convinced by now that it will never change.

Cthulhu_ 2y ago

It apparently sells merchandising for their own brand though.

michaeltiller 2y ago
The Modelica Association is a non-profit that publishes the specification, the standard library and all conference proceedings for free. We sell merch in part because people in the Modelica community like the language and like to show it but also as a way to fund the not for profit activities.
jrowen 2y ago
Downvoted but relevant...nothing says corporate bullshit like a niche programming language with logos and merch featured far more prominently than examples or explanation...
- michaeltiller 2y ago
  Just to be clear, there is absolutely nothing "corporate" about that web site. It is a non-profit organization.
  - jrowen 2y ago
    Sorry, I guess that was rude, I don't know anything about it, just a snap judgment of the landing page.

PittleyDunkin 2y ago

Modelica Language -> Modelica By Example -> https://mbe.modelica.university/ https://mbe.modelica.university/ Took me under 5 seconds to find.

observationist 2y ago
[flagged]
- alwa 2y ago
  I wonder if some of those words might be terms-of-art, written with a specialist rather than a generalist audience in mind.
- porcoda 2y ago
  Accessible to whom? I work in a field that uses things like Modelica and it reads just fine to me.

bglazer 2y ago

Here are some examples. Looks like a simplified framework for writing physical and electrical system simulations. https://mbe.modelica.university/ https://mbe.modelica.university/

spookie 2y ago
I wouldn't say simplified. You can model a lot of systems with it. It's pretty good.
michaeltiller 2y ago
Over 20 years ago I modeled an internal combustion engine, an automatic transmission and a multibody chassis model all in a single model. IIRC, the model had something like 250,000 equations in it and it modeled combustion, hydraulics, friction, and 3D rigid body motion. It is capable of far more than simple models. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=2234d4c76767d2609df20bfff4a31b7e794d4531 https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...
- bobim 2y ago
  Ah! You're the author of Modelica by example?
  - michaeltiller 2y ago
    Yes. And "Introduction to Physical Modeling with Modelica". I also built the Modelica Playground (which I deliberately didn't link to because a thundering herd of HN readers would have crashed it).
    - bobim 2y ago
      Nice to cross your path, I got the first one to kickstart myself some years ago (and still struggling with evaporation / condensation). Would you recommend the second to introduce a colleague to OpenModelica? He is into gPROMS but will lose access to the software at retirement. Sidenote: invest in software with freedom to operate and good knowledge reusability.

nativeit 2y ago

The first link for “Modelica Language” includes tutorials and examples. Five seconds of clicking around got me to: > Let us consider an extremely simple differential equation: x = (1-X) Looking at this equation, we see there is only one variable, x This equation can be represented in Modelica as follows: model FirstOrder Real x; equation der(x) = 1-x; end FirstOrder; This code starts with the keyword model which is used to indicate the start of the model definition. The model keyword is followed by the model name, FirstOrder. This, in turn, is followed by a declaration of all the variables we are interested in. [et cetera]

qart 2y ago

As someone who is a curious outsider to Modelica, it piqued my interest a few years ago when I found out that this language lets you write equations more directly than most other programming languages. Take the ideal gas law, for example, PV = nRT, which has 5 identifiers. In most programming languages, you'd have to keep only one variable to the left, that is assigned to, e.g. T=PV/nR, and a similar set of equations if you want to determine any of the other variables, given the rest. In Modelica, the same equation, expressed as you would in natural math, works for determining the unknown, based on the knowns. https://mbe.modelica.university/behavior/equations/electrical/ https://mbe.modelica.university/behavior/equations/electrica... I don't know much beyond this.

alhirzel 2y ago
This is generally referred to as an acausal modeling environment - you don't need to bring the causality of mathematical relationships, just bring the relationships. There are several other tools in this space, not the least prevalent of which is Mathworks' Simscape product line [1]. Wolfram has a solution that is also very similar to Modelica [2]. Finally, I believe that you will find ModelingToolkit.jl [3] worth a look (along with Julia in general) if your interest is piqued here by Modelica. I believe MTK is a big slice of the future of acausal modeling tools. [1] https://www.mathworks.com/products/simscape.html https://www.mathworks.com/products/simscape.html [2] https://www.wolfram.com/system-modeler/ https://www.wolfram.com/system-modeler/ [3] https://docs.sciml.ai/ModelingToolkit/stable/examples/spring_mass/ https://docs.sciml.ai/ModelingToolkit/stable/examples/spring...
- buescher 2y ago
  Wolfram SystemModeler is a Modelica implementation.

JKCalhoun 2y ago

I wonder if anyone is keeping a list of the new languages that come out every year.

michaeltiller 2y ago
Modelica is nearly 30 years old, BTW.
- JKCalhoun 2y ago
  TIL. Thanks.

pixelpoet 2y ago

Another day, another nondescript product name on HN for Russian roulette clicking. Dare to say anything about it, get downvoted into a smoking hole in the ground (e.g. by webdevs who assume everyone else is), yadda yadda... I'm pretty convinced by now that it will never change.