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Use of Ln in a formula

Use of Ln in a formula

Use of Ln in a formula

(OP)
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

RE: Use of Ln in a formula

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

RE: Use of Ln in a formula

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

Derek

RE: Use of Ln in a formula

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.

RE: Use of Ln in a formula

(OP)
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.

RE: Use of Ln in a formula

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.

RE: Use of Ln in a formula

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

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