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Problem with sign function sign(u)

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Hello,

I am trying to sketch a rounded square with the parametric curve functionality using x(t)=2.1sign(cos(t))(abs(cos(t)))^(1/2) and y(t)=2.1sign(sin(t))(abs(sin(t)))^(1/2), and i get a warning message which i assume is related with the sign function because the warning doesn't appear when it is not included in the above parametric relationships.

Do you have any clue why this happens? Does anyone has experience with the sign function Thanks miko


1 Reply Last Post Feb 17, 2020, 3:00 a.m. EST
Magnus Ringh COMSOL Employee

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Posted: 5 years ago Feb 17, 2020, 3:00 a.m. EST

Hello Miko,

These expressions should work fine. For general information, the correct COMSOL syntax is

2.1sign(cos(t))(abs(cos(t)))^(1/2) 2.1sign(sin(t))(abs(sin(t)))^(1/2)

(or use "sqrt(...)" instead of "^(1/2)")

I'm not sure what kind of warning you see. If it's about the tolerance, which is what I get with the default settings, you can adjust it in the Advanced Settings section of the settings window for the Parametric Curve feature.

Best regards, Magnus Ringh, COMSOL

Hello Miko, These expressions should work fine. For general information, the correct COMSOL syntax is 2.1*sign(cos(t))*(abs(cos(t)))^(1/2) 2.1*sign(sin(t))*(abs(sin(t)))^(1/2) (or use "sqrt(...)" instead of "^(1/2)") I'm not sure what kind of warning you see. If it's about the tolerance, which is what I get with the default settings, you can adjust it in the **Advanced Settings** section of the settings window for the Parametric Curve feature. Best regards, Magnus Ringh, COMSOL

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