While loop oddity

[Michael Aivaliotis]

Original Post:

http://forums.ni.com/ni/board/message?boar...ssage.id=200378

I was trying to make a bit of code in 7.1, win2k do the following:

If an index is contained in a row of a 2D array of integers, output all of the integers for that row, otherwise, just output that index.

My somewhat convoluted VI to do so is attached.

Now, am I overthinking this (which I've been known to do ), or is it actually taking a modification of the row downstream and modifying the input array?

I checked this on an 8.20 eval, win xp machine with the same results.

Thanks,

Joe Z.

Reported: # 40DAF67U

Download File:post-2-1156914149.vi

[LAVA 1.0 Content]

Original Post:

http://forums.ni.com/ni/board/message?boar...ssage.id=200378

Reported: # 40DAF67U

This is really weird.... Can I trust my LabVIEW to compute correctly after bugs like this and the constant loop bug?

[Wolfram]

This is really weird.... Can I trust my LabVIEW to compute correctly after bugs like this and the constant loop bug?

Strange thing like the "For Loop" bug in 7.1.

I guess, we can expect LV 8.2.1

I also found out the same behaviour in LV 7.1.1 and 8.0.1

Wolfram

[Jacemdom]

:headbang: :!:

[LAVA 1.0 Content]

:headbang: :!:

These kind of bugs normally indicate that the software architecture is too complicated and not modular, and the bugs arise from the fact that new functionality is added to an environment where it doesn't fit to the architecture. :thumbdown:

[Gepponline]

This bug worries me a lot...how can i go on if i can not rely on labview???

So i made some test.

The error occur at the indexing in the while loop.

If we carry the 2d array into the while loop and extract each element using the index of the cycle no more error occurres.

So....there must be an explanation to this thing...

I don't like auto indexing in the while loop...i use them only when are useful even to determine the number of cycles of the for loops. Can it be relate to this bug?

Three Cycles..same operations... only while loop is wrong...

It's not possible such a bug!

and.....if the problem is the "+1" module combined with the while loop?

If we substitute the "+1" with a sum with an array of 1 the problem don't occur.

Download File:post-1899-1157618194.vi

[LAVA 1.0 Content]

and.....if the problem is the "+1" module combined with the while loop?

The error occurs also with '-x' so I suspect it occurs with all 'in-place' operations which do not create a new buffer but modify present buffer.

[daal]

Hi, I found that if you enable the Show folding feature the error don't occur anymore :thumbup:

Dany

Download File:post-223-1157980624.vi

[Grampa_of_Oliva_n_Eden]

Hi, I found that if you enable the Show folding feature the error don't occur anymore :thumbup:

Dany

Download File:post-223-1157980624.vi

Yikes!

Talk about being on the horns of a dilema!

Since I generally do not auto-index While Loops I'll leeve the "Show Constant folding" off and try to remember not to auto-index on while loops.

Ben

[Gepponline]

yes but....

in LbVIEW 7.1 there is no "show folding" options...... :headbang: :headbang:

[LAVA 1.0 Content]

Hi, I found that if you enable the Show folding feature the error don't occur anymore

What the F... ? How can visualization option have anything to do with how LabVIEW generates code? Is there a name collision, on bug collides with another and both desappear... :headbang: :beer:

[Craig Smith]

Original Post:

http://forums.ni.com/ni/board/message?boar...ssage.id=200378

Reported: # 40DAF67U

This is indeed a bug in LabVIEW's inplaceness algorithm, the result of an overzealous optimization, having to do with using auto-indexing input tunnels on a While Loop inside another loop. It is slated to be fixed in the next maintenance release.

Craig Smith

LabVIEW R&D

National Instruments

[jaegen]

This is indeed a bug in LabVIEW's inplaceness algorithm, the result of an overzealous optimization, having to do with using auto-indexing input tunnels on a While Loop inside another loop. It is slated to be fixed in the next maintenance release.

Craig Smith

LabVIEW R&D

National Instruments

Well, I guess now we know we're going to see 8.2.1 before 8.3 or 9.0

Jaegen

[Bob Y.]

Well, I guess now we know we're going to see 8.2.1 before 8.3 or 9.0

Jaegen

:!: Yes, but we will have to wait a year until LabVIEW is 21 years old to see LabVIEW 8.21

[jaegen]

:!: Yes, but we will have to wait a year until LabVIEW is 21 years old to see LabVIEW 8.21

Thank you - that brightened my otherwise rather grey day fighting with upgrading a project to 8.2. It is rapidly becoming counter-productive: See here, and here.

Jaegen

[etrnaly]

Hi, I found that if you enable the Show folding feature the error don't occur anymore :thumbup:

Dany

Download File:post-223-1157980624.vi

Setting the folding option didn't seem to fix that bug. What I did figure out was that putting the index of the for loop into the while loop caused the bug.

[jzoller]

QUOTE(Michael_Aivaliotis @ Aug 29 2006, 10:02 PM)

Original Post:http://forums.ni.com/ni/board/message?boar...ssage.id=200378 Reported: # 40DAF67U

Apologies to Michael for interrupting... just updating.

Fixed in 8.2.1.

http://zone.ni.com/devzone/cda/tut/p/id/5674

Bug # 40DAF67U

Joe Z.