iLogic Parameter function behaviour

[Anonymous]

In the attached part, I don't understand why these two rules produce a different result:

Rule 1
If Parameter("glass") = 21.5 Then
     MsgBox("Standard")
Else
     MsgBox("Non-Standard")
End If

Message - Non-Standard

Rule 2
If glass = 21.5 Then
     MsgBox("Standard")
Else
     MsgBox("Non-Standard")
End If

Message - Standard

I need to use the Parameter("glass") format as it's going to be an external rule, but I'm totally miffed as to why its producing the result it is.

Anyone able to provide some insight?

[b_sharanraj]

I feel like its not considering the decimal values.

Change that to some whole numbers and check once its working fine. Don't know exactly why its not taking decimal values.

[Anonymous]

Hi @b_sharanraj

It's not that... Try it with 17.5 instead of 21.5 and it works as it should

[b_sharanraj]

You can try like below code it may help you

Dim Temp_Glass as Single
Temp_Glass = Parameter("Glass") 

If Temp_Glass = 21.5 Then
MsgBox("Standard")
Else
MsgBox("Non Standard")
End If

If Glass = 21.5 Then
MsgBox("Standard")
Else
MsgBox("Non Standard")
End If

[Anonymous]

Works normally when I change the value to 20.5 or 22.5. It doesn't like 21.5 

[Anonymous]

Your method does work around the problem, thanks for that.

I'm hoping someone at Autodesk can confirm if this is a bug?

[b_sharanraj]

Bravo @Anonymous

You find out a bug 

Yes it have some problem only with 21.5 

[LukeDavenport · Accepted solution]

There's already an interesting thread on this kind of rounding problem:

https://forums.autodesk.com/t5/inventor-customization/attack-Of-the-DoubleForEquals/td-p/5808334

(be warned its quite a complex thread!)

To summarise it - the issue is already logged as a bug with Autodesk. The suggested workaround to reduce these problems is to declare parameter values as Decimal.

Dim b As Decimal = Parameter("glass")

This works fine.

Although here's a couple more alternatives for you if you'd rather not have to 'Dim' your parameter on a separate line:

Alternative 1:

c = Parameter.Param("glass").Value * 10 

This is so-called 'advanced iLogic syntax' and it gets you access to the parameter object in the API. Note you would have to multiply by 10 if you’re working in mm (due to Inventor’s internal units of cm)

Alternative 2:

d = ThisApplication.ActiveEditDocument.ComponentDefinition.Parameters("glass").Value * 10 

' This is pure API code - obviously the path to the parameter object can be shortened!

Hope this helps,

Luke

[LukeDavenport]

I should also have pointed out that for Alternative 1 and 2 above you don't actually need to declare the parameter value, so you don't need to write (for instance):

Dim c As Decimal = Parameter.Param("glass").Value * 10 

You can simply write:

c = Parameter.Param("glass").Value * 10 

If anyone is interested in the reason for this, its because the methods shown in Alternative 1 and 2 return a Double object (for numeric 'dimension' parameters), which compares fine with other numbers, but the Parameter("glass") method returns an iLogic DoubleForEquals object - which doesn't currently play well when compared to other numbers.

[HermJan.Otterman]

hello,

did you try to "Round" the parameter before the compair?

I had some issues where 3 is not 3, but 3.000000001134252..

[Anonymous]

@LukeDavenport Thanks for the insight Luke, I can work with one of these methods.