Elliptic integral in LV a different result

[Mal123]

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?

[GerdW]

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.)

[Mal123]

Hi,

Attached code.

Best regards 

[altenbach · Accepted solution]

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". 😄

[altenbach]

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).

[Mal123]

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