Use of Ln in a formula 1

[Joeydee]

I am trying to use the natural log function in a model to calculate a length, however I keep receiving the following alert- "Units are not homogeneous (m into Constant). We advise you to specify precise units for constants, otherwise the International System Units will be the default. (Ex:10->10mm or MyRealParameter->MyrealParamerter*1mm." I have checked the settings and they all appear to have the correct units - any ideas?

Thanks in advance

Joey Dee

 

[DBezaire]

Joey - it appears that you are trying to use a math function against a parameter. For example, you have a length parameter A and B. A = B + 2in
If you do not specify the "in", Catia does not understand which unit to apply. It could be mm, m, ft....

Regards,
Derek

 

[DBezaire]

Joey - when in doubt check Tools - Options - Units, for the various options of units --> parameter type.

Derek

 

[Azrael]

Check the units on both side of the operator, they should match. Note that in general you can't add or subtract a non unit parameter with one with parameter but you can multiple and divide.

 

[Joeydee]

I have checked the settings and they are all similar. The formula I am trying to use is - Ln((length(`Geometrical Set.1\Line.30`)+length(`Geometrical Set.1\Multi Output.17 (Project)\Project.30`)) /60 ) but still giving the error as before even placing "in" after each length.

 

[DBezaire]

Joey - this might be of some use.

http://2htts.com/CATBlog/index.php?itemid=38

Ferdo made a tutorial on parameters and design tables.

Regards,
Derek

 

[catiajim]

Your Ln function is a function of length(elem). A Ln function can only be applied to a real number. Try dividing the whole thing by 60in. This will divide the length by a length, and give you a real number.

 

[DBezaire]

And make sure the parameter type you are filling with the formula is a real number as this is the result