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If Condition evaluation?
Posted Jul 13, 2017, 4:13 a.m. EDT 1 Reply
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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!
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 Jul 13, 2017, 5:24 a.m. EDT
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Posted:
7 years ago
Hi,
Your second version is correct.
The first will be interpreted as ((0<x)<1)=(1<1)=0
Regards,
Henrik
Your second version is correct.
The first will be interpreted as ((0<x)<1)=(1<1)=0
Regards,
Henrik