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If Condition evaluation?

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Hey there,

I am struggling with the evaluation of if conditions within COMSOL.

I have an equation that shall be evaluated if x is between 0 and 1. Say:

y = f(x) * (0<x<1)

Assuming x is between 0 and 1, the expression (0<x<1) should be evaluated as 1, shouldn´t it? But it is not. COMSOL evaluates the if condition as 0. Hence, COMSOL returns y=0, which is not correct.

I also tried it this way:

y = f(x) * (0<x) * (x<1)

Here both if conditions are evaluated as 1, resulting in the correct solution y = f(x).

I monitored the values of the if expressions with Point Probe Expressions during the calculation procedure.

Why is there a difference in the evaluation of the same if conditions?

Thanks for your effort!


1 Reply Last Post 13.07.2017, 05:24 GMT-4
Henrik Sönnerlind COMSOL Employee

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Posted: 7 years ago 13.07.2017, 05:24 GMT-4
Hi,

Your second version is correct.

The first will be interpreted as ((0<x)<1)=(1<1)=0

Regards,
Henrik
Hi, Your second version is correct. The first will be interpreted as ((0

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