Formula node bitwise OR has a bug?

Hello everyone,
I am trying to do a bitwise OR with 32 bits in an formula node. It seems that the OR operation produces unexpected results if the most significant bit is set. For example if I do:
0x00000000 OR 0xffffffff I would expect 0xffffffff. Instead I get 0x80000000. In binary this looks like:
00000000000000000000000000000000 OR
11111111111111111111111111111111 EQUALS
10000000000000000000000000000000
Please see the attached minimal example for comparison of some example values. The output with using blocks is exactly the one I would expect and is also included in the example.
I am using Labview Version 14.0f1 on Windows 7 Professional.
This might also be in connection with the following currently unresolved bug:
48016
3P7CBB4Q
http://www.ni.com/product-documentation/52150/en/#48016_by_Category
However that that bug is for unsigned int32 and the suggested workaround is to use signed 32 bit integer, which nevertheless fails in the provided example code.
If someone could have a look and tell me if this is a bug or if I am misunderstanding somtheing that would be great. I am already starting to go crazy.
Best regards and thanks in advance
Saali
Attachments:
Minimal_Bug_example.vi ‏10 KB

No, actually this bug is different from what is documented.The documented bug happens with uInt32 and the documentation specifically suggests to use Int32 as a workaround for the known bug:
"2. Use signed 32-bit integers instead of unsigned 32-bit integers in the formula node."
However this is exactly what fails in my case when I use OR. I thought this might be some valuable information for the people trying to fix that bug. (Which seems to be hard to find, as it has been around so long and screws up very basic operations.)
It might also be that NI does not really care for that bug because most people don't use the formula node for basic bit arithmetic. Anyway, I just wanted to put the information out somewhere for the next person who has that problem to find. I guess the lesson I learned from this conversation is don't trust the formual node to much for doing low-level bit stuff...
Best regards
Saali

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Message Edited by geirove on 06-13-2008 06:23 AM
Geir Ove

geirove wrote:
JoeLabView wrote:
Hi Geir,
It is not a bug.  ............
The node does not recognize localized decimal separators."
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Failing to do so may cause serious, expensive and very hard to trace errors.
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In 6.0.2 it returns 1 in both cases.
"Adam Russell" wrote in message
news:ajcc8d$1a266r$[email protected]..
>
> "Bill Atkins" wrote in message
> news:[email protected]..
> > Pass a 3-element integer array, containing values 5, 6, 7 into a
> > formula node as input variable x. Pass variable y out. The formula
> > node contains:
> > int32 y;
> > y = (x[2]-x[1]);
> > My result is 6. If the parentheses are removed, the answer is 1.
> > Apparently adding the parentheses causes the expression to be
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>
> It works correctly in 6.1. I'm at home so I can't t
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>
>

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Ravens Fan wrote:
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Attachments:
cast_failure.llb ‏23 KB

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Problems with bit shift left in Formula Node

Hi,
Sorry but my English is not good.
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float32 valorAmostra;
int16 indiceAmostra;
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int8 i;
for(i=0; i<5; i++)
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Solved!
Go to Solution.

Portuguese:
Olá,
Existe um bug no LabVIEW para esta operação. Este bug deverá ser corrigido em versões futuras. Uma solução para esta situação é utilizar um int32 ao invés de um ulnt32.
Qualquer dúvida por favor entre em contato.
Obrigado.
English:
I investigated the problem you are having, and it turns out that it is a bug that has already been reported and documented. The work around for it is to use int32 rather than uInt32.
Thanks.
Luciano Borges
R&D Engineer
Pirelli Brazil

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Attachments:
LV script test.png ‏62 KB
LV script test.vi ‏18 KB

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Formula node

Hi everyone.
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Attachments:
formula node.vi ‏87 KB

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Message Edited by GerdW on 02-27-2008 05:11 PM
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formula node1.vi ‏87 KB

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Conditional Formula Node demo.vi ‏13 KB

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shift (LV7.1).vi ‏19 KB

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Attachments:
ArrayFormulaNode.vi ‏23 KB

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Hello
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Nghtcwrlr
********************Kudos are alwayzz Welcome !! ******************
Attachments:
Sine square in formulanode.vi ‏18 KB

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dear friend
I'm trying to use formula node to solve a problem because I make this program using c at the begining.
It runs perfectly in turbo c, but somehow it doesn't work in the formula node.
I try to debug my source code, and I find that the formula node seems can't read the true value in
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for ( i = 0 ; i < sopa; i++ )
j = 1;
ep[i][0] = pa[i];
ep[i][1] = np[ep[i][0]][0];
while ( ep[i][j-1] != exit )
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This is the part that I think the problem might be.
if ( np[ep[i][j-1]][k] != -1 && (pc[ep[i][j-1]][ep[i][j]] + pc[ep[i][j]][exit] >= pc[ep[i][j-1]][np[ep[i][j-1]][k]] + pc[np[ep[i][j-1]][k]][exit] ) && (pc[ep[i][j-1]][np[ep[i][j-1]][k]] == org[ep[i][j-1]][np[ep[i][j-1]][k]] ))
ep[i][j] = np[ep[i][j-1]][k];
I state that "np[ep[i][j-1]][k] != -1" but I do get the value -1 in the array "ep".
Could someone tell me why I get -1 in the array?
I hope I can finally do it all by labview not using formula node,but array like "pc[ep[i][j-1]][np[ep[i][j-1]][k]] "
seems very hard to wire in labview. Could someone give me some good advices of doing this?
Thanks for your help

altenbach 已寫:
normanshi wrote:
ep[i][0] = pa[i];                                          (A)
ep[i][1] = np[ep[i][0]][0];                            (B)
...    if ( np[ep[i][j-1]][k] != -1 && ... )          (C)
      ep[i][j] = np[ep[i][j-1]][k];                       (D)
I state that "np[ep[i][j-1]][k] != -1" but I do get the value -1 in the array "ep".
Could someone tell me why I get -1 in the array?
I hope I can finally do it all by labview not using formula node,but array like "pc[ep[i][j-1]][np[ep[i][j-1]][k]] "
seems very hard to wire in labview. Could someone give me some good advices of doing this?
There are many possible scenarios to get a -1 in the ep output. For example if the -1 gets already written in step (A) or (B) at a certain index, and that index does not get overwritten in step (D). You are indexing all over the place! Is there some bounds checking on the array contents? What are typical inputs and array sizes?
I'm sure about that the -1 doesn't get already written in step (A) or (B) because ep[i][0] and ep[i][1] is fine. What really makes me confuse is that sometimes ep array has the value like this.
That means it does overwritten some value in step (D). The -1 should never be written into it because I have already state that np[ep[i][j-1]][k] != -1. Somehow I still get -1,and this is really strange! I'm indexing all over the place becuase I can't figure out a better way to achieve my requirement.
I think I should briefly tell you what I'm trying to do. In this program,I input some values which means the distance from one point to another. Then I use floyd's all pairs shortest-path algorithm to find all the shortest distance. Finally I want to find out the "shortest path". I mean like from point 4 to point 0,the shortest path might be like 4 -> 2 -> 1 -> 0, and what the formula node part do is trying to find out this "shortest path". Maybe you can give me some better advice of doing this, I have been thinking a better way to do it for about two months. I think I'm really not good at this.
I try to do it all by labview ,but again I get a strange problem. This time the ep[i][j-1] doesn't get the correct value. In the first time i=0 j-1=0 ep[i][j-1] = 1,but the second time i = 0 j-1 = 1 ep[i][j-1] = 0. This makes the "ep[i][j-1]!=exit" get the incorrect boolean value. The ep[i][j-1] should be 2,not 0. I try to use highlight to find if I make any mistake, but I can't one.This is the input and I put the labview program in attached file (temp4.vi).
Could you help me find out why this happened?
Thanks for your help altenbach!
由 normanshi 在 08-19-2006 10:06 PM 上編輯的訊息
Attachments:
temp4.vi ‏191 KB
ep.jpg ‏10 KB
input.jpg ‏9 KB

Formula node bitwise OR has a bug?

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