Failure of dimensional analysis for a rule

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Day
Day 2023-9-21
评论： Day 2023-9-27
Hi,
I have a rule y=x^0.35. x has the dimension of mass. An error message showed up saying that the exponent must be an integer constant. How can I handle this situation as this rule is very important in my model?
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Day
Day 2023-9-21
The model was developed using the Simbiology app without writing codes.
Torsten
Torsten 2023-9-21
编辑：Torsten 2023-9-21
Can't you assign a unit to y instead of letting Simbiology compute it for you as kg^0.35 ? And why is it possible if the exponent is an integer ? Are you sure that this is really a dimensional problem ?

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Arthur Goldsipe
Arthur Goldsipe 2023-9-21
When you enable dimensional analysis (or unit conversion) in SimBiology, fractional exponents can only be applied to dimensionless quantities. So you could write your rule as y=y0*(x/x0)^0.35, where x and x0 have the same units, and y0 is the value of y when x=x0.

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Walter Roberson
Walter Roberson 2023-9-21
I am baffled about what unit (grams ^ 0.35) would be. Should that be interpreted as (grams ^ (35/100) so that the unit would be "the 100'th root of grams to the 35'th power" ? Or should it be interpreted as (grams ^ (7/20)) ? so that the unit would be "the 20'th root of grams to the 7'th power" ?
Mind you, I also struggle with the physical meaning of something like y = sqrt(x) when x is mass.
If this is a situation of "never mind the dimensional continuity for now, the math works out" then you are going to have to strip the units from the item, make the math transformation, and add units back to the result.
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