Error calculatio​n with LabView

Question

I am just courious, maybe someone did such error estimation with LabView, and can show me a better approach.
Scenario:
I have the following function with one variable (x), K is a constant:
y = ( -1/2*K + SQRT( 1/4*K^2 - (4*K - K^2)*(x^2 - x) ) ) / (2-1/2*K);
 I have x as an input, and I know the error of x at certain positions.
I would like to estimate the error of the result y values from the given x values.
Since this is not a monotonic function (the first derivative changes sign), the standard Gauss error propagation formula with the first partial derivative is not enough here. The first derivative of the above function is simple to
get analytically, but the second would be a pain to calculate...
How would you treate such a problem with LabView, maybe some kind of numerical derivation to get second (or maybe even third derivative from the Taylor series?) derivative?
Right now we just use a more simple error estimation:
we slightly over-estimate the error of y in the following way: 
delta_y = MAX { ABS(y(x)-y(x-error)) ; ABS(y(x)-y(x+error)) }
 So we take the higher difference as an error.
How would you do it differently if you have LabView under your hands? (LabVew pro 2013 + almost all toolkits)
I could not find error calculation related VIs in the drop menu, are there any?
Thanks for any advice!

Answer 1

Blokk wrote:
I use formula nodes often
I think my post would be more appropriate in the Idea Exchange forum. Maybe someone can move it there...
The idea would be that to have ready made VIs for general often used error calculations...(Gauss error propagation, confidence level, definitions, etc..)
So the LV user could save dev time...?
If you have some formula nodes ready to go that might be useful for others, but don't quite have them packaged as VIs yet, it might be faster (and go through less bureaucracy) to just post them up here. I'm sure someone could repackage them according to standard LV connection panes (maybe even do some clever icon designing) and would post them on one of the popular LV Tools repositories.
As far as I can tell by just following threads on this forum, the NI engineers already have so many suggestions, fixes, etc. that getting a brand new "this would be nice" Idea added to the LV shipping program is going to take a little less than forever to implement, especially if it would only involve combining functions already available. (No indictment of you, NI engineers, it's just that we users seem to be really good at producing Ideas and we do outnumber you .)
Cameron
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