# LabVIEW

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## Elliptic integral in LV a different result

Hi All,

In LabVIEW I found a different result for the elliptic integral of first kind.

For example if I put input k= 0.994673

LV give a result K(k)= 4.01

All other routines, this is an example:

https://keisan.casio.com/exec/system/1180573454

Give a result K(k)= 3.6656...

Someone could explain me why?

What is the correct result?

Message 1 of 6
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## Re: Elliptic integral in LV a different result

Hi Mal,

maybe you should also attach the VI you are using to calculate the integral…

(Many of us prefer older LabVIEW versions, so you might "Save for Previous" to provide your VI for LV2019 or so in case you use a recent LabVIEW version.)

Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 2 of 6
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## Re: Elliptic integral in LV a different result

Hi,

Attached code.

Best regards

Message 3 of 6
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Solution
Accepted by Mal123

## Re: Elliptic integral in LV a different result

It seems LabVIEW defines the k slightly differently.

You get the correct values if you square the input as follows.

I am not familiar enough with the details of the parameter conventions or who is more "right". 😄

Message 4 of 6
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## Re: Elliptic integral in LV a different result

LabVIEW probably should have called the input terminal "m" instead of "k". (see here)

Note that Matlab also uses "m" (i.e. k²) as input, but names it correctly. (details).

Message 5 of 6
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## Re: Elliptic integral in LV a different result

Dear Altenbach,

Thank you very much, I was going crazy,

I was deceived by the fact that the second kind result was about the same number rounded.

Best regards

Message 6 of 6
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