formula node output on the right hand side

[Husain111]

I want to use formula node to find the  independent variable (right hans side equation). For simiplicty let us say y=x+z. When I make z as the output it gave wrong answer but when the y is output, it works fine. I have a more complicated equation which prevent modification to make the output on the left hand side. I attached the VI

[johnsold]

That is the way the formula node works.

If you cannot derive an equation with the unlknown on the left, you will need to use some kind of iterative, numerical approximation to the solution. There are several options for such methods, depending on the form of your equations and data.

Lynn

[kosist90]

The reason is that when you write "y = x+z", equation on the ouput will give you result of "y", how it is written. To find "z", you need explicitly write "z = y - x", then it will work. LabVIEW will not do the magic to find missing value in the equation.

[altenbach]

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@Husain111 wrote:

I want to use formula node to find the  independent variable (right hans side equation). For simiplicty let us say y=x+z. When I make z as the output it gave wrong answer but when the y is output, it works fine. I have a more complicated equation which prevent modification to make the output on the left hand side. I attached the VI

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LabVIEW does not contain a symbolic math solver. If you cannot rewrite the formula in the way you want (try wolfram alpha!), I would probably use newton-raphson to find the solution. It ypically converges very fast. Make sure there is only one unique solution and that you know a reasonable guess.

[Husain111]

Thank you for reply

It seems the problem is more tricky than I though. I attached a snapshoot for the equation the unknown is the (alpha/bet) the rest are known. I would like to hear you suggestion. Do you think using Matlab script a good option?

[johnsold]

What does the NT/eff terminology represent? Is the NT exponentiation and the eff a subscript, or something else?

Do you have measured values for f? 

Can you epxlain what the equation represents physically?

Lynn

[Husain111]

O.K

I wrote the equation in more simple way in word equation. So, the unknown is x and all other samples are feeded from previous calculations

[johnsold]

I am not sure what you did but the file you posted containts only one character "P".

Many people on the Forum will not open files in formats other than NI file formats, text, .jpg, .png, or .pdf becasue of the possiblilty of malware.

Lynn

[altenbach]

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@johnsold wrote:

I am not sure what you did but the file you posted containts only one character "P".

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It is a word document containing a formula as follows:

 

(Lynn, maye you don't have the equation editor installed or you are using some other program to open word files).

[johnsold]

I read it as a binary file with the datatype = string. Duh... Stupid Read From Binary File function defaults to reading only one byte! 

OpenOffice displays it as a blank page without any indication that it missed some content.

Lynn