NI survey quiz question

[Jonnie_5]

So I was playing with the Survey quiz at:
http://research.ni.com/run/celvskillsquiz
and one of the questions is:
What is the value in Feedback Answer after the third iteration of the loop below?

The quiz says the correct answer is 8.  I say it's 4 as Feedback Answer is wired to the last loop value of the feedback node:
I=0 (first iteration) = 1 (initialization value)
I=1 (second iteration) = 2
I=2 (third iteration) = 4

Who's right?

Message Edited by Jonnie 5 on 07-28-2006 10:23 AM

Message Edited by Jonnie 5 on 07-28-2006 10:25 AM

[jochynator]

it's 8 - just try...

[Joe_H]

It should be 8.

Message Edited by Jhoskins on 07-28-2006 11:06 AM

[Dennis_Knutson]

I get values of 1,2,4,8,16 so I think the quiz is wrong.

Message Edited by Dennis Knutson on 07-28-2006 09:11 AM

[Jonnie_5]

ahhh... the voice of reason!  Thank you Dennis!
jochynator  -> your vi doesn't match the example.  note that the output should be wired to the Last Loop side of the feedback node (the arrow head's side).

Message Edited by Jonnie 5 on 07-28-2006 11:13 AM

[Darren]

Yup...notice the subtle difference between the screenshot and jochynator's "just try" example...the original screenshot has a feed forward node, and jochynator's example has a feedback node.  Check the LabVIEW Help on Feedback Nodes for more information about the differences.  But yes, as the screenshot is given, with a feed forward node, '4' is the correct answer.  You can see this with the attached VI, saved in LabVIEW 7.0.  It's easiest to see the behavior with Execution Highlighting turned on.

-D

[Joe_H]

Man I did the same thing yep 4 is correct

[jochynator]

I'm sorry, too slow thinking too fast working 🙂 Can me somebody tell how to create forward node? I can only create feedback.

[Jonnie_5]

it's the same structure - it just flips around depending on the surrounding wires (annoyingly at times!).
For more on it's direction see:
http://digital.ni.com/public.nsf/allkb/6a0c9bb733d8f2ee86256e9800508e69

[altenbach]

One of the reasons I typically stick with shift registers. Feedback/feedforward nodes are just way too confusing....

Just right-click in the feedback node and convert it to a shift register. Suddenly, the code makes much more sense. 😄