Array output from formula node

How to get an array output from the formula node.I am trying to use a for loop inside the formula node and want an array output.

You cannot place a For or While Loop inside the formula node.
Here is what the Help Description says about the syntax inside the Formula Node:
Formula Node
Evaluates mathematical formulas and expressions similar to C on the block diagram. The following built-in functions are allowed in formulas: abs, acos, acosh, asin, asinh, atan, atan2, atanh, ceil, cos, cosh, cot, csc, exp, expm1, floor, getexp, getman, int, intrz, ln, lnp1, log, log2, max, min, mod, pow, rand, rem, sec, sign, sin, sinc, sinh, sizeOfDim, sqrt, tan, tanh. There are some differences between the parser in the Mathematics VIs and the Formula Node.
Place on the block diagram
Find on the Functions palette
Refer to Creating Formula Nodes and Formula Node Syntax for more information about the Formula Node and the Formula Node syntax.
Note The Formula Node accepts only the period (.) as a decimal separator. The node does not recognize localized decimal separators.
<SCRIPT type=text/javascript>if (typeof(writeVarRefs)=="function"){writeVarRefs("763");}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvrthelp763) != "undefined"){document.writeln(lvrthelp763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvfpga763) != "undefined"){document.writeln(lvfpga763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvemb763) != "undefined"){document.writeln(lvemb763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvpdahelp763) != "undefined"){document.writeln(lvpdahelp763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvtpchelp763) != "undefined"){document.writeln(lvtpchelp763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvblackfin763) != "undefined"){document.writeln(lvblackfin763)}</SCRIPT>
<SCRIPT type=text/javascript> if(typeof(lvdsp763) != "undefined"){document.writeln(lvdsp763)}</SCRIPT>
Example
Refer to the Create Function with Formula Node VI in the labview\examples\general\structs.llb for an example of using the Formula Node.

Similar Messages

Array output from formula node with input variable as array size

Hi,
I have created a formula node with an array output called al, but I get an error "you have connected a scalar type to an array with that type".
I declare the output as follows..
float64 al[len_as];
where len_as is an scalar input to the formula node.
It only works when I put a number as.
float64 al[5];
,but I don't know beforehand how many elements I need, so I cannot use this.
Please help! This is so stupid.
Thanks

Don't define your array in your formula node.
Initialize the array as the size you want and pass it in as an input into the formula node.
Are you sure you even need to use a formula node? Can you implement your formula using all native LabVIEW functions?
Message Edited by Ravens Fan on 10-07-2009 11:51 PM
Attachments:
Example_VI_BD.png ‏3 KB

Boolean input & output from formula node?

Hi All,
How do you declare input and output variables to be boolean in the formula node. See attached example, I want leak and prev to be of type boolean.
Thanks,
Sean

Here's an example of how you could simplify the boolean portion of the code:
oh yeah... pretend the boolean constant and indicator are Shared Variables
Message Edited by Ray.R on 10-13-2009 01:06 PM
Attachments:
reducedCode.PNG ‏4 KB

Array Handling in Formula Node

I have attached a simple VI wherein I want to take an input array, look at its size and use the size of the input array as the size of the output array. The output array needs to be declared. I want to be able to use the size of the input array "N" as the size of the output array too. The size of the input array changes dynamically based on my simulation needs. I dont want to modify the size of the array in the declaration every time I change the array size in simulation.
I have tried using b[N] instead of b[10] in the formula node. However LV does not seem to accept this and gives me a syntax error.
Attachments:
Array Handling in Formula node.vi ‏8 KB

AGovi wrote:
However I require to use complicated formulas such as
If a simple formula is easier in G, a complicated formula will also be easier in G.
Actually, it will scale better. Since graphical code is 2D, doubling the code will make it only 1.4x (sqrt2) larger in each dimension, while the formula will double in lenght.
LabVIEW Champion . Do more with less code and in less time .

Array init in formula node

I would like to cut and past in a list of comma seperated numbers and initialize an array of float32. Something like this would work in C.
float32 data[5] = {0,1,2,3,4};
Labview does not like this syntax when using a formula node. I have to do the following instead
float32 data[5];
data[0] = 0;
data[1] = 1;
What is the correct syntax for initializing arrays in lavview using a formula node. I would be amazed if Labview does not have this basic functionality.
thanks in advance
jim bob

labview_noob wrote:
ttt, no one?
Probably because we are using LabVIEW to get away from text based code.
(I don't know if there is a syntax for the formula node, it's been too long. )
If you have LabVIEW 8.0 or higher, you can use matlab like sytax in a mathscript node. Of course you could just paste your list into a string constant and get the values with "spreadsheet string to array".
Message Edited by altenbach on 07-25-2007 12:24 AM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
ArrayFormula.png ‏13 KB

How can I increment the index of an array in a formula node?

Hi,
I need some help with the formula node. I need an array, that increment every iteration of the code in the formula node. I need it to save amplitudes.
I thought i could do this with i++; i is the variable for my index.
Martin
Solved!
Go to Solution.

Hello,
does it sound well to you ?
@+
Tinnitus
ps: sorry posts mixed
Message Edité par tinnitus le 12-15-2008 03:05 AM
CLAD / Labview 2011, Win Xp
Mission d'une semaine- à plusieurs mois laissez moi un MP...
RP et Midi-pyrénées .Km+++ si possibilité de télétravail
Kudos always accepted / Les petits clicks jaunes sont toujours appréciés
Don't forget to valid a good answer / pensez à valider une réponse correcte
Attachments:
inc_node.vi ‏6 KB

Cannot Access Shortcut Menu for Adding Input/Output in Formula Node

This is a wierd problem. I cannot access the shortcut menu in formula node. I right click the border, nothing happens. Anyone run into this before? Is there any other way to add inputs and outputs?
I am running Vision Builder AI and want to use a formula node in my calculator tool.
Solved!
Go to Solution.

As the saying goes, "when you hear hoofbeats, think horses and not zebras". Let's get a few things out of the way.
Is the VI in edit mode?
Is autotool on?
Drop a fresh FN on a New VI and try it again.
The only other way I know to add/remove inputs is scripting, let's not go there.
I have had a few issues with context menus, very few which persisted past a LV and/or computer restart, so I won't rule out a zebra just yet.

Array data in formula node

I want to take the Y value (being the amplitute) from the input signal and put it into a formula node. I keep getting the error signal as in the attached VI. Is there a way of seperating the value in labview?
Attachments:
Formula signal.vi ‏32 KB

Hi Cork,
yes, it's possible! And WTH: you can do it without a formula node with ready-to-use functions!
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Variable size array output from dynamic dispatch class method on FPGA

I have a Parent class on the FPGA that will serve as a template/framework for future code that will be developed. I had planned on creating a child class and overriding a couple methods. The child class constant would be dropped on the block diagram so the compiler wouldn't have any trouble figuring out which method (parent's or child's) should be used (i.e. the parent's method will never actually be used and won't be compiled with the main code). The output of one of the methods is an array. This array will have a different size depending on the application. I defined the array size as variable. In the child method, there is no question about the size of the array so the compiler should be able to figure it out. However, when I try to compile, I get an error about the array size. I can't figure out any way around it. Any thought would be greatly appreciated!
Thanks, Patrick
Solved!
Go to Solution.
Attachments:
FPGA Test.zip ‏1194 KB

Wait what?
Can we use dynamic dispatch VIs on FPGA? Really? I was completely unaware of this. Obviously the dependencies need to be constant and known at compile time but...... This would have saved me a lot of headaches in the last few months.
Since which LV version is this supported?
Say hello to my little friend.
RFC 2323 FHE-Compliant

How do I get an array output on a Formula Node?

My problem is simply that I cannot figure out how to get an output on a Formula Node to be an array. Documentation states that "you must declare local arrays and output arrays in the Formula Node" but doesn't say anything more than than. Attempts to put something like "float32 out[100];" for an array output called "out" fail.
If anybody knows how you can do this or even knows if it is possible I would appriciate your help.
Thanks,
Naveen

I found a typo in the formula node I was doing that was making the output not be an array. I don't think I was getting the error before but I was going to put together an example VI to attach here and I found it. So, thanks for your help even tho it was a stupid little mistake on my part.

String array into formula node

Hello,
I am taking data from SQL, I am getting multiple rows of data for many different devices. I would like to wire the data into a formula node so I can sepearate and sort via script. However, I am getting an error for "Polymorphic terminal cannot accept this data type". Is there a work around? Can I not wire in a string array to a formula node.
/r
Travo

There are lots of basic string VIs that you can use to parse the string and separate out the individual fields. I would recommend "programming" your application using script nodes. Use the native language. LabVIEW is a fully functional and capable programming language.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

How do I determine array size in a formula node

I am feeding an array into a formula node to perform an operation on. However the size of the array can be an arbitrary size. How can I determine its size to use for iterating through a for loop?
I suppose that I could add another input that is fed with the array size from the array palate but I would like to know if it can be done inside the formula node itself.

Your own advice is the only and best one.
greetings from the Netherlands

Formula node to 2d array

Hey there
I have a problem with my formula Node. I want to recieve a pictue from my camera and generate a 2d-array of the greyscalevalues. That works so far. Now i recieve an array with values between 0 and 4096 (because I have a 12-Bit picture).
Now the problem i have is, that the camera can dim the values, which are bigger than 2048. I tried to fix that problem with a Formula Node. But now i have the problem, that i can't connect the formula node to the intensity graph anymore.
I use the Labview Version 2013 and the camera is connectet with an ethernet-wire.
Can somebody please show me, how i can generate a 2d-array after the formula node?
Thanks
Attachments:
Formula Node.vi ‏282 KB

Hey muks
Yes, i take the picture from the camera and convert it to a 2d-array with the "ImageToArray" block.
Attachments:
ImageToArray.png ‏13 KB

Atan2 equivalent in a Formula Node?

Does anyone have an atan2 (2-input inverse arctangent) equivalent for use in a Formula Node? I was surprised to see that such a common function wasn't supported in Formula Nodes. Without it, my easily readable Formula Node equations get junked and become a nightmare of LabVIEW math symbols. Is there a way to call the atan2 VI (or any other VI for that matter) from within a Formula Node?

Hello,
You are correct, this function is not supported in Formula Nodes, and there is not a way to call VIs from formula nodes. However, the below solution might be what you need:
Is this the correct definition of atan2:
if y = atan2(a,b), then tan(y) = (a/b)
If so, could we define a and b, and use the formula node function atan(a/b)? This may not be the most elegant solution, but it seems like it would do the trick with minimal headache. I attached a VI showing this idea.
Hope this helps!
Liz Fausak
National Instruments
Attachments:
atan2FNode.vi ‏10 KB
61atan2FNode.vi ‏10 KB
60atan2FNode.vi ‏8 KB

Formula node calculation error

Hi all,
I am expecting the output of formula node as the value of "c" input variable. but it outputs NaN. I am attaching jpeg file illustrating that.
Clarification would be appreciated.
Kousy
Attachments:
Formula 1.JPG ‏21 KB

Hi Kousy,
look at attached example...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
Interpolate_threshold.vi ‏15 KB

Array output from formula node

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