Formula Node variable assignment problems

I have a formula node with the follwing:
Inputs:E,X,T,PD,I
OutputsK,PD
The statement inside the formula node is:
if (Eelse if (PD=1) if (E else if (E<=X) ;
else PK=I, PD=1;
The logic seems to be working the way I want, the problem is in the last else statement. PK is never assigned the value of I. however, PD is assigned the value of 1. There are no errors indicated.
The source of the I input is the iteration # of the For loop where this formula node is located.
Anyone see what I am missing??
Thanks,
Mike

Mike,
In comparisons, == should be used instead of =. This is a very common mistake, and a reason that forumla nodes should be avoided if possible (except of course for very long formulae that would require a lot of nodes.
It looks like your code would be better represented with LabVIEW nodes instead of in a formula node (for readability - there is no performance difference.)
Also, you may wish to reconsider using an Input variable that has the same name as an output variable. Try using PDi and PDo, or PD1 and PD2 instead.
Good luck.

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Hi,
I don't see exactly what you're trying to do here.
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Wiebe.
"DrON" wrote in message
news:506500000008000000E
[email protected]..
> I need in Formula Node to assign to the variable value 4000000000!!!
> What kind of variable it should be???
>
> i've just tryed to write unsigned in32, but it does not understand
> 'unsogned'... But i need variable to be unsigned, because the max
> value = 4000000000... So, how can i solve this probleme???

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Thanks,
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Attachments:
1.png ‏5 KB
1.png ‏5 KB

Your screen shot shows if(N!=1||N!=2). That is if N is not equal to 1 OR N is not equal to 2. Well, since N can never be equal to 1 and 2 at the same time, of course the statemenet always evaluates to True.
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"Alfio" wrote:
>>I have found a "serious" problem converting VI from LV 5.1.1 to 6iI have
same "big" equations for density calculation with upper 65 coefficients>and
3 o more inputs variables.>Everything goes well and fast in 5.1.1, when I
open this VI in LV 6i there>is automatically conversion>of exponential symbol
(from "^" to "**") with non apparent problem,>but the result of equation
is WRONG, very, very incorrect (from 0 in 5.1.1>to same negative milliard...).>I
tried with more different equations and the results are similar...>For the
last: when I re-convert my VI in version 5 and run it in LV 5.1.1>everything
re-work PERFECTLY! Strange.>Have I found a "terrible" BUG?>Someone have found
the same problem?>Do you have some idea?
>I will wait some news from you.:-)>Thanks
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Hi Alfio
Some times ago I had a simmilar problem but with labview 4.x. My equation
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Certified LabVIEW Developer
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Solved!
Go to Solution.
Attachments:
Calculate Discharge coeff.vi ‏7 KB

Ha ha ha, thank goodness for Mac's. When I went back and replaced all the "-" with "-" it fixed the problem. The problem was that I had copied/pasted from a pdf document, and what was displayed in the formula node wasn't what it was seeing! So much for WYSIWYG!
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Message Edited by LV_Pro on 10-21-2009 12:39 PM
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Certified LabVIEW Developer
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Problems with bit shift left in Formula Node

Hi,
Sorry but my English is not good.
I'm trying to execute a bit shift left in the Formula Node, but the shift left is not working as I expected.
uInt32 parametro[5];
float32 valorAmostra;
int16 indiceAmostra;
uInt8 indiceResposta;
int16 controle;
int32 valor;
int8 i;
for(i=0; i<5; i++)
parametro[i]=param[i];
valor = parametro[5]<<16 | parametro[4]<<8 | parametro[3];
controle = parametro[1]<<8 | parametro[0];
indiceAmostra = (controle & 0x3FF);
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if((valor & 0x800000) == 0x800000)
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the input param array is of the type uInt8, as I saw in other topics that does not shift with uInt8,
I copy the values of param array to parametro which is of type uInt32, but still did not work.
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Can someone help me please?
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

Array index problem in formula node

dear friend
I'm trying to use formula node to solve a problem because I make this program using c at the begining.
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I try to debug my source code, and I find that the formula node seems can't read the true value in
the array.
Here is the code in the formula node.
int32 i,j,k;
for ( i = 0 ; i < sopa; i++ )
j = 1;
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ep[i][1] = np[ep[i][0]][0];
while ( ep[i][j-1] != exit )
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      ep[i][j] = np[ep[i][j-1]][k];
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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];
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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

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