Gamma function in formula node

I am running LabView V.6.1 and try to use the gamma function in a formula node.
According to the HELP text ''Formula Node and Expression Node Functions'', the syntax for the Gamma funtion is gamma(x), but this leads to the block diagram error ''Formula node: Undefined variable''.
Other functions (like exp(x), sqrt(x) etc.) work.
Thanks for helping.

Hi,
we ran into this one a little while ago. The help is a little misleading. The Gamma function actually only works with the Expression Nodes, and not the Formula nodes.
Go to the labview help file, and search for "Differences Between the Parser in the Mathematics VIs and the Formula Node "
Also refer to the following link for a bit more information :
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=50650000000800000020540000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0&USEARCHCONTEXT_QUESTION_0=%22Square%22+function+in+formula+node&USEARCHCONTEXT_QUESTION_S=0
it's a bit long winded, but be patient - the information is in there.
Hope that helps
S.
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********************Kudos are alwayzz Welcome !! ******************

Why a formula node? Just use plain LabVIEW!!!
Your specifications seem odd and incomplete. What is the range of t you want? "Vo vs t" only makes sense if V=constant unless you want a 3D or intensity graph: V(Vo, t).
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Hi Nadav, Sacha and Martin
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Square_Function.vi ‏16 KB
Square_Fucntion_2.vi ‏26 KB
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myRGBtoLAB.vi ‏32 KB

Wow Chris!
That is one impressive formula node! In terms of computational efficiency, I wouldn't expect there to be a lot of difference between the formula node and separate VIs. Stll, I have attached two sub VIs that I think implement the two repeated areas of the formula node code.
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"... after all, He's not a tame lion..."
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Thanks.
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Go to Solution.

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

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Formula Node
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Really need Min(a,b) and Max(a,b) function in "Eval formula node"

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"Eval Parsed Formula Node VI" does not return outputs in predefined order

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Formula node

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I have a problem with the formula node.
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formula node.vi ‏87 KB

Hi matomato,
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Message Edited by GerdW on 02-27-2008 05:11 PM
Best regards,
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Muthu92 wrote:
Thank you for your reply. It is very useful for me. But i can't give conditional operator in that operator. It is showing error.
My Test cases
A[0]+A[1]>150
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If those are your exact statements, then they don't make sense in a formula node. You have to use them in an if-statement or some other type of control logic. This mimics text-based programming languages such as C... See here for instructions on formula node syntax: http://zone.ni.com/reference/en-XX/help/371361G-01/lvhowto/formula_node_syntax/
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EDIT2:
I stand corrected. After trying to create an example and digging through the LabVIEW Help, I stumbled across this:
Differences between the Parser in the Mathematics VIs and the Formula Node
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Functions—atan2, max, min, mod, pow, rem, and sizeOfDim are not valid. You can use these functions in a Formula Node or use their corresponding LabVIEW functions.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Solved!
Go to Solution.

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Message Edited by smercurio_fc on 07-01-2009 11:24 AM
Attachments:
Example_VI.png ‏3 KB

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