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Add Spice3-specific infiniteTime constant #4481

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Add Spice3-specific infiniteTime constant #4481

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484fd1d
Added Spice3-specific infiniteTime constant
casella Oct 17, 2024
3842c62
Updated constant description based on @bilderbuchi's advice
casella Oct 18, 2024
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14 changes: 10 additions & 4 deletions Modelica/Electrical/Spice3.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -3134,8 +3134,8 @@ Christoph Clauß
parameter SI.Time TD = 0.0 "Delay time";
parameter SI.Time TR(start=1) "Rise time";
parameter SI.Time TF = TR "Fall time";
parameter SI.Time PW = Modelica.Constants.inf "Pulse width";
parameter SI.Time PER= Modelica.Constants.inf "Period";
parameter SI.Time PW = Spice3.Constants.infiniteTime "Pulse width";
parameter SI.Time PER= Spice3.Constants.infiniteTime "Period";

protected
parameter SI.Time Trising=TR "End time of rising phase within one period";
Expand Down Expand Up @@ -3512,8 +3512,8 @@ If, e.g., time = 1.0, the voltage v = 0.0 (before event), 1.0 (after event)
parameter SI.Time TD = 0.0 "Delay time";
parameter SI.Time TR(start=1) "Rise time";
parameter SI.Time TF = TR "Fall time";
parameter SI.Time PW = Modelica.Constants.inf "Pulse width";
parameter SI.Time PER= Modelica.Constants.inf "Period";
parameter SI.Time PW = Spice3.Constants.infiniteTime "Pulse width";
parameter SI.Time PER= Spice3.Constants.infiniteTime "Period";

protected
parameter SI.Time Trising=TR "End time of rising phase within one period";
Expand Down Expand Up @@ -4435,6 +4435,12 @@ on the model behaviour.
</html>"));
end Types;

package Constants "Spice3-specific constants"
extends Modelica.Icons.Package;

constant Modelica.Units.SI.Time infiniteTime= 1e20 "Very large time horizon (3e12 years) avoiding overflow in time computations";
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While we are defining new (local) constants, what do you think about not enlarging the scope of the problem of the unfortunate (incorrect) naming of Modelica.Constants.inf, and give this constant a more accurate name, e.g. hugeTime or largeTime or something like that, instead of infinity, which it is not?

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@casella casella Oct 21, 2024 •
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It's infinite for all practical purposes. Large or huge have no definite meaning, large with respect to what? Infinite time period and width means you'll never see a falling edge, so you'll get the rising edge only.

If you look at the parameter window and you see that both period and width are "infinite" it is clear that there will be no periodic behaviour if you leave those parameters to their default values. Which I guess was the original intent of the authors.

The problem with using Modelica.Constants.inf here is not in the name, it's in the value.

But I guess we are over-discussing this issue here...

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Okay, then.

end Constants;

package Internal
"Collection of functions and records derived from the C++ Spice library"
extends Modelica.Icons.InternalPackage;
Expand Down