Using General Polynomial Fit VI with waveform graph

Hello gurus ,
I would like to ask how to use General Polynomial Fit VI with waveform graph not GraphXY .
Waveform graph is giving me an array of values not X , Y i think , what should i do ?
Thanks in advance
Solved!
Go to Solution.

Hi Omar,
i changed the shipped Labview Example to use the General Polynomial Fit VI with a waveform graph.
But why don't you want to use a X-Y-Graph?
Regards
DianaS
Attachments:
test.vi ‏37 KB

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How to use General Polynomial Fit

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Very new to LabVIEW (mostly use Matlab) and I'm trying to use the General Polynomial Fit VI and I have found the built-in help for LabVIEW very lacking and the examples not much better. The help says that, among other things, the inputs are the x and y data points. I have my data in 1D arrays of double, but this is apparently the wrong format for the VI it states that the VI needs it in double. This would imply that it only takes one data point at at time? Do you have to build it up one point at a time in a loop?
Thanks in advance for any help,
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Oops, nevermind. Accidentally selected the point by point variation...

Different general polynomial fit results

Hello,
I've encountered a strange problem using the general polynomial fit: It seems that the outcome of this vi is computer dependent...
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Attachments:
get_polyline.vi ‏37 KB

Well, taking a 20th order polynomial does not make a lot of sense anyway. What are you trying to achieve? There are probably better ways to do whatever you want to do here. You are dealing with extreme intermediary values (e.g. 1500^20=3.32e+63) so a slight reordering in operation could change the outcome.
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General Polynomial Fit

I need to fit a polynomial function and extract the coefficients a0, a1, etc, of my data. But in the General Polynomial Fit i have to especified the order, is there any way to find automatically the polynomial order and then extract the coefficients? Thank you.

Thinking about this question again, I`m not sure I`ve answered the correct question at all.
My original method (Scanning different fit orders) will give aou an N-order Polynomial which fits the signal well, but the assumption that your signal is then also an N-order Polynomial is generally false. If you are simply looking for a polynomial which well describes your signal, this is OK.
If you are dealing with simple clean signals then you MIGHT be able to make assumptions on the signal type based on various fit coefficients, but if you`re trying to understand fundamentals of a real-world complex signal based on fit-algorithm errors, I would be, in addition to the other respondants, very cautious. I`m not a very good mathmatecian (I love that the fit algorith
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Solved!
Go to Solution.

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How to connect with waveform graph?

hi
i would like to know how to simulate wave form graph the input is randon number ?My problem is i cannot connect with wave form graph...
can u show me example..like using arrary...or something else..i looking forward ur reply
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I have an example that you may want to look at here.
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My application uses a Waveform Graph to plot data acquired from a
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One approach would be to enable graph cursors and have the user click and
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Mike Sachs
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"Rod B. Nussbaumer" wrote in message
news:afal8d$37q$[email protected]..
> My application uses a Waveform Graph to plot data acquired from a
> scope. The application does some analysis of the waveform data
> and then uses features within the waveform as the basis for
> controlling some external devices. The features (peaks) that
> are to be used must be selected by a human operator. Ideally,
> this would be d
one by having the user click on/near the peaks
> of interest.
>
> I haven't seen anything in Labview that looks like I can trap
> mouse clicks within a screen widget. Have I missed that level
> of functionality, or is there no feasible way of implementing
> such an interface?
>
> I am presently using a system of tables and sliders to allow
> the users to select peaks, but the users are not totally happy
> with the method.
>
> I am using Labview 5.1 on Sun Solaris.
>
> Thanks.
>
> --- Rod
>
>

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Regards,
vijtin
Solved!
Go to Solution.

hi,
X0 is the offset and X is the multiplier. So the graph will start at a cetain offset and will aa to that the delta value times the multiplier.
e.g.
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Hope this helps
Kind regards,
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It seems, i cannot explain the question in good way
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By the way, I found more:
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No, GerdW, it doesn't work
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chebychev Ploynomial fit.PNG ‏48 KB
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Using General Polynomial Fit VI with waveform graph

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