How is this possible? 1 parameter, 2 values.

[Aidenj]

One simple parameter, two values, at the same time, right next to each other. 

??

Your thoughts?

8.000 = 7.997 ?

[Aidenj]

Moreover, when I type "8.000" into the right side leg, it reverts to 7.997.  But it allows me to specify 8.000 on the left leg. 

[Aidenj]

For all practical purposes, it doesn't matter to me if Revit is off by .003 on this family, I'm just curious how the software can store two values in one parameter at the same time.

[barthbradley]

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@Aidenj wrote:

I'm just curious how the software can store two values in one parameter at the same time.

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A single parameter can only yield one value.  A parameter could return one value based on other parameter values.   Is that what you are talking about?  

https://www.revitforum.org/showthread.php/1046-Revit-Formulas-for-quot-everyday-quot-usage

[Aidenj]

It makes sense when the value of a parameter is derived from a formula, or is dependent in some other way on a changeable variable. In this case, as you can see from the original post image, the parameter, "shingle side length" is just a simple value set by the user directly. I set it to 8.000. Revit shows both 8.000 and 7.997 at the same time in the actual family environment modeling window. That's what threw me for a loop. I'm wondering now if the reason it's doing this is because the view plane is out of alignment, just slightly, with the plane of the right half of the sketch, and would cause the screen-space measurement to return a smaller value to reflect how the sketch space lines land on the view plane.

[barthbradley]

Is it a Reporting Parameter? 

[Aidenj]

It's not a reporting parameter.

[cbcarch]

set the angle to 135 degrees and see if they are both equal.

[barthbradley]

.

[ToanDN]

Can you share the family?

[Aidenj]

I thought I shared it in the original post, but it was a post I made about a similar topic. Attaching it now. Thanks!

[Aidenj]

The angle is set by the slope through a formula - so it's hard for me to perfectly control it. The model is available for download if you'd like to play with it? I'm attaching it here if your are interested.

[barthbradley]

Try this approach...

[barthbradley]

Shingle using same approach...

[ToanDN]

It doesn't look like your image and 8 is 8.

[Aidenj]

You are right ToanDN. I checked the file I posted and it doesn't exhibit the strange behavior I asked about originally. I'm guessing it was from an intermediate file. The image in the original post is authentic, but I have not been able to find the version of that family that produced the unusual behavior.

[Aidenj]

Hi barthbradley - thanks for looking into this. I tried out your file and it works very well. The reason I posted initially rose more out of a curiousness about the computer science behind the phenomenon, vs the practicality of getting a roof shingle to be parametrically perfect. But your file is indeed perfect, so thanks!

[barthbradley]

You're welcome. 

I did those two Families before you posted  yours. That's the reason one is rod-shaped which is what I extrapolated from your screenshot. Then I saw the word "Shingle" and realized what the shape exactly was suppose to be.  Hence, the second one I did for you.  When I opened your RFA, I noticed you were using the sweep approach as well - although you did it a little differently.  Perhaps my way will be more stable.  Don't know.  Sounds like you are no longer having issues with yours. Maybe it was a fluke issue.        

Good luck.