Kcal are not recognized in OpenModelica

[Terryxz1]

Kcal units are not recongized by the native libraries in modelica.

[MarekMatejak]

In my opinion, this is an issue of OpenModelica, not Physiolibrary.
E.g. in Dymola are supported special unit conversion defined such as :

Physiolibrary/Physiolibrary/Resources/DisplayUnits/displayunit.mos

Line 13 in f6bcb40

defineUnitConversion("J", "kcal", 1/4186.8 );

However, you can ignore these error messages of OpenModelica and just run the simulation in SI units such as J (Joule).

[Terryxz1]

Makes sense. I realized the simulation worked after sending the issue to you. This was while running Minimal Circulation. Question: Can OpenModelica developers be prompted to update their units? Thanks! Sent from Outlook for Android<https://aka.ms/AAb9ysg>

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________________________________ From: Marek Matejak ***@***.***> Sent: Sunday, November 2, 2025 3:41:53 AM To: MarekMatejak/Physiolibrary ***@***.***> Cc: Terryxz1 ***@***.***>; Author ***@***.***> Subject: Re: [MarekMatejak/Physiolibrary] Kcal are not recognized in OpenModelica (Issue #44) [https://avatars.githubusercontent.com/u/6085966?s=20&v=4]MarekMatejak left a comment (MarekMatejak/Physiolibrary#44)<#44 (comment)> In my opinion, this is an issue of OpenModelica, not Physiolibrary. E.g. in Dymola are supported special unit conversion defined such as : https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Resources/DisplayUnits/displayunit.mos#L13 However, you can ignore these error messages of OpenModelica and just run the simulation in SI units such as J (Joule). — Reply to this email directly, view it on GitHub<#44 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/BCTKXJ2D5XJZBSMBX27BMC332W7VDAVCNFSM6AAAAACKWVXZ62VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTINZXGY2DIOBXHA>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[MarekMatejak]

All values in Physiolibrary are internaly calculated in SI units. E.g. volumes are in m3 with nominal 10^-6 (as tolerance in mL), see

Physiolibrary/Physiolibrary/Types.mo

Line 1587 in f6bcb40

type Volume = Modelica.Units.SI.Volume(displayUnit = "ml", nominal = 1e-6, min = 0, max = Modelica.Constants.inf);

.

However, user can use the "display unit" during setting parameters or ploting outputs. This has no implact to the simulation, because also these values are stored in SI units.

Some Modelica enviroments such as Dymola allows you to define even your own "display units" with your "own conversion" such as was done in https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Resources/DisplayUnits/displayunit.mos

Today, the usage of "display units" in OpenModelica is limited only to fixed set of predefined units.

[Terryxz1]

Thank you that clarifies the issue. OpenModelica is optimized for different applications. - I will look into the developers forum for more information on this topic; it may be possible to prompt the developers if it has not been done already. Thanks! T

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On Sun, Nov 2, 2025, 12:13 p.m. Marek Matejak ***@***.***> wrote: *MarekMatejak* left a comment (MarekMatejak/Physiolibrary#44) <#44 (comment)> All values in Physiolibrary are internaly calculated in SI units. E.g. volumes are in m3 with nominal 10^-6 (as tolerance in mL), see https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Types.mo#L1587 . However, user can use the "display unit" during setting parameters or ploting outputs. This has no implact to the simulation, because also these values are stored in SI units. Some Modelica enviroments such as Dymola allows you to define even your own "display units" with your "own conversion" such as was done in https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Resources/DisplayUnits/displayunit.mos Today, the usage of "display units" in OpenModelica is limited only to fixed set of predefined units. — Reply to this email directly, view it on GitHub <#44 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BCTKXJZZ6T4U6U2HTIFCXMT32Y3VNAVCNFSM6AAAAACKWVXZ62VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTINZYGEYTQOBSGY> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[Terryxz1]

P.S. Reference to the unit conversion library. Modelica.SIunits.Conversions https://share.google/vuq3juY7ssaGE70U7 Looks like that needs to be extended to include the units in Physiolibrary.

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On Sun, Nov 2, 2025, 12:13 p.m. Marek Matejak ***@***.***> wrote: *MarekMatejak* left a comment (MarekMatejak/Physiolibrary#44) <#44 (comment)> All values in Physiolibrary are internaly calculated in SI units. E.g. volumes are in m3 with nominal 10^-6 (as tolerance in mL), see https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Types.mo#L1587 . However, user can use the "display unit" during setting parameters or ploting outputs. This has no implact to the simulation, because also these values are stored in SI units. Some Modelica enviroments such as Dymola allows you to define even your own "display units" with your "own conversion" such as was done in https://github.com/MarekMatejak/Physiolibrary/blob/f6bcb409e3be998f7948e3d71901773d7af7525a/Physiolibrary/Resources/DisplayUnits/displayunit.mos Today, the usage of "display units" in OpenModelica is limited only to fixed set of predefined units. — Reply to this email directly, view it on GitHub <#44 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BCTKXJZZ6T4U6U2HTIFCXMT32Y3VNAVCNFSM6AAAAACKWVXZ62VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTINZYGEYTQOBSGY> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[MarekMatejak]

Yes, Modelica Standard Library (current version is here: https://github.com/modelica/ModelicaStandardLibrary ) defines also the functions to recalculate units, but this is also only the usage of units from Modelica environment. This is not the place where you can define the new "display unit".

May be here is the place where non-SI units in OpenModelica are defined:
https://github.com/OpenModelica/OpenModelica/blob/1d11bb5831193295cf5d6873eb065f17f664e59c/OMCompiler/Compiler/runtime/unitparser.cpp#L903