NaN input to a sub-vi

[@nk]

Hi,

I have got a sub vi for finding out the derivative which has got a double input.

The sub-vi is inside a while loop and input going is double value only. but inside the sub-vi it is showing "NaN" input and the sub vi is giving an " NaN" output.

Thanks in advance

[altenbach]

What you are saying does not make a lot of sense. Can you also show us the calling program?

(Instead of the express VI, it would seem more reasonable to use the ptbypt derivative function.)

[@nk]

Ya actually I too felt because the input is going as a double and then inside sub Vi it is showing NaN .

That is why i got confused.

I have attached an extraction vi ,whose output is E1 and E2 from these two values am finding out the dx/dt( derivative). I have used Ni usb 5133 for the input of that extraction Vi

[altenbach]

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@nk wrote:

Ya actually I too felt because the input is going as a double and then inside sub Vi it is showing NaN .

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Well, NaN is a DBL.

Sorry, I don't understand how the extraction VI you now show relates to the original problem. Please explain.

[@nk]

The output of extraction vi is E1 and E2( two double values), these values are given to this threshold.vi like E1 as input to one sub vi , E2 to the other.

[altenbach]

E1 and E2 are arrays. The input of the subVI is a scalar. You simply need to describe things better.

Why can't you show us a version that actually calls the subVI in question?

[@nk]

E1 and E2 are arrays , I am sorry x/y and x/y 2 are given as inputs for the sub vi.

[altenbach · Accepted solution]

Why don't you make yours and our life easier by simply attaching the actual VI instead of an oversized truncated image?

Since the same subVI is used in parallel on many different inputs, you need to make it reentrant, else you only get one instance onf the internal express VI and it will scramble everything, guaranteed!

As I said before, I recommend to used the ptbypt derivative VI. That's all you need.

[@nk]

Thank you for the help and consideration