Formula node- using C

Hi there,
I need to create a vector and for that I am using the formula node. I am doing that in C ( in which I really am a beginner) whereas in MATLAB the program some time runs some time it does not.
Attached is the program, the error list says:
Error on line 3 is marked by a '#' character: " int32 j; double# Rv[14]; Iv[14]; for "
Can anyone help?
thank you in advance
Solved!
Go to Solution.
Attachments:
sum.vi ‏8 KB

You have 2 syntax errors on that line. The proper term is not double but float64. And separate the two arrays with a comma and not the end of statement semicolon.
Make it look like this and the broken run arrow goes away.
float64 Rv[14], Iv[14];

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Dead loop in formula node

Hi,
I have encountered the following problem in a formula node. Everything seems simple and right. But there is no output and the loop goes on forever. The sizes of both input arrays are the same. Need your advice. Thanks.
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Attachments:
Algorithm.vi ‏11 KB

Look, I am far out on a limb here, because I am not a C programmer. Whatever you're doing would make more sense from a FORTRAN point of view.
The LabVIEW formula node uses BNF notation (check the help), which is in many ways C like. So the syntax for a FOR loop is:
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Do a google search on "C For loop" and you might find for example pages like:
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http://www.geocities.com/learnprogramming123/Clesson8Beginner.htm
Your condExpression is "n1-1", which, during the execution of the node is a constant. For example if you array size is 50, n1-1=49, FOREVER! The condition is never true so the loop will never stop.
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Hi,
I am working on editing a VI to make it much easier to understand (for colleagues and non LV users). For one reason or another, the VI's creators did not fully make use of the power of case structures and other structure types. In the application we need it for, the instrument cycles and repeats measurements on several objects. We are interested in measuring the motor currents for several motors in the system. As it stands now, for each sample object's run, there is a separate sub-vi diagram which displays its waveform trace and several indicators such as max current, time at max, etc. That code was contained within a T/F case structure and copied and pasted 20 plus times.... Obviously the vi became extrememly cluttered and needed a huge screen to see. The trigger for the current case structures is an EQUALS comparison between one input (which is the sample object counter; and this part I will likely leave unchanged since it makes a lot of sense already) and a constant which was defined 1 through 20+ for case.
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Thanks for the help!

Is your formula node doing anything else besides what is shown?
Why don't you just wire the value that is going into it at X directly into the selector of the case structure?
Attachments:
Example_VI_BD.png ‏2 KB

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You should be able to declare it using:
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Solved!
Go to Solution.

replace || with &&
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Solved!
Go to Solution.
Attachments:
fabs.jpg ‏14 KB
error.jpg ‏11 KB

xiaoquan wrote:
Yes, I tried. It can be accurate to six decimal places. I tink maybe it is the limit of DBL. Do you know some other way to increase the accuracy? Thank you very much!
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AbsDBL.png ‏6 KB

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>
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>  
>  
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Log10 used in a formula node

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Message Edited by GerdW on 12-17-2008 08:26 PM
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Solved!
Go to Solution.

Hi Jathin,
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-D
Message Edited by Darren on 02-09-2006 01:32 PM
Darren Nattinger, CLA
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Attachments:
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Formula node- using C

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