Labview 2012 compound arithmetic function breaks VI using units

[KeithTK]

Thanks for putting up a bug report.  🙂

After finding that Gy unit appear I think I'll do one of the other work-arounds besides a divide by default unit. 😉

[PhillipBrooks]

I worked for a calibration house years ago and thought that units would be great for controlling the integrity of the data I created. They sucked beyond belief and I wasted several months trying to make them work before discovering that the problem was not me.

If this example indeed proves to be a new bug, then there is no conclusion that I can come to other than NI does not have tests for or use units in their code.

It's simple; fix them or get skip them all together!

Vote for this idea:

http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Make-units-work-all-the-way-or-skip-them/idi-p/1803510

[Matthew_Kelton]

So I think we can safely say that as of today, do not use compound arithmetic with LV2012 and values with units assigned to them.

[crossrulz]

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@KeithTK wrote:

Ok, this is getting ridiculous.

Scrubbing old code for this bug I came across this:

A simple velocity multiplied by a unitless number yields units of... Gy?  I had to check what a Gy even was!  Somehow velocity = radiation??  That is just sad NI.

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Per Wikipedia, 1Gy = 1m^2/s^2.  So it would appear to me that it is the same bug as found earlier (additional multiply by base unit).

[Matthew_Kelton]

I agree it is obvious that the compund arithmetic object using units is not in LabVIEW's test suite, as it would have failed miserably.

[KeithTK]

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@crossrulz wrote:

Per Wikipedia, 1Gy = 1m^2/s^2.  So it would appear to me that it is the same bug as found earlier (additional multiply by base unit).

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Velocity^2 = Gy

...you learn something new every day!  

[Daniel-H]

Hey Guys,

This definitely looks like a serious bug to me.

I'll update to our R&D immediately. I would think this is something we want to address.

Regards,

Daniel

Applications Engineering

National Instruments

http://www.ni.com/support 

[Roy_F]

This was reported to R&D (CAR 368375) for further investigation. This worked, we broke it in 2012, it's a high priority issue and we expect to have a fix available "soon" (unfortunately, I can't be more specific).

Roy Faltesek

Senior Group Manager

LabVIEW R&D, Product Support

[GregSands]

Just came across the same bug - my example is computing the area of a circle:

In related news, the Square function still doesn't handle units properly some 5 years after being reported.  It even has a 5-digit CAR by the looks - how many of those are still unresolved?

[rolfk]

Many years ago I experiemnted with units in LabVIEW (it's a feature that existed even in LabVIEW 3 or so). My conclusions were that it is a pitta to do so as there are many situations where you have to convert between units and non-units to make it work. Some of those situations are because of lack of unit support for certain LabVIEW nodes, some are much more fundamental, basically requiring such conversions no matter how perfectly LabVIEW would deal with units. I abandoned units then and never looked back. And I know in fact nobody who really felt different about units then and since, and that also means it is never really tested, both in Betas and apparently not even in the LabVIEW unit tests.

My guess about solving known bugs in respect to units is that it is all lumped together in one big Meta Bug that also includes fixing the entire LabVIEW unit system, and that is a really difficult thing to do, if at all possible. My experiments back then led me to believe, that it is basically an unsolvable problem if you talk about making units a fully featured attribute of all elements in LabVIEW.