Introduction to the tutorial of curve fitting - curve example of non-linear editing

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• Introduction to the tutorial of curve fitting - find a function

  I'm new to programming in Labview (and programming in general) and so I'm learning the different functions in Labview that are likely to be relevant to the work that I do.  One of the functions I'll take advantage in Labview is the curve of the functions.  To this end, I found a number of tutorials that are available in the area of the developer, and the plan is to work my way through some tutorials apply in order to understand the processes involved (and how to use features etc.).

  The tutorial that I am currently working my way through is the Introduction to the tutorial Curve Fitting, and is where I am currently blocked.  To work through the linear curve of squares vi, as shown in Figure 3 of the tutorial, I can't seem to find the function that the linear data vi and the vi curve are interconnected and which connects to the curve of the linear model.  When I say that I can't find the function I want to say that I can't find the feature with the Schwaar icon in the Labview version that I use currently (it is the Labview 8.6 development system).  Can I get help with the function I need to use?

  I note, however, that the tutorial was written in 2006.  Would be - why I'm unable to find the function indicated (that is to say, he has changed since this tutorial was written)? If this is the reason why, anyone knows what is now the correct function?

  The tutorial can be found here: http://zone.ni.com/devzone/cda/tut/p/id/7669.

  Thanks for your help.

  Hey Scottum,

  This is the function table to build in the range of table in respect of the programming.

  If you hover over it in top and bottom of the function, you should see two small squares.  Mouse over the squares and your mouse turns into a vertical head double arrow.  You can drag the mouse in the vertical direction to expand the service to include more inputs.

  Hope this helps,

• Fit Gaussian Peak and non-linear curve Fit on small data differ from the PEAK of origin made

  Hi all

  I'm developing a program in which I have to adjust the curve of Gauss on only 4 or 5 data points. When I use the Gaussian Ridge Fit or adjustment of the curve non-linear, it connects linearly all the points so that other editing software like origin's curve fitting of Gauss on the same set of data that I have attached two images is LabVIEW with Fit Gaussian of Peak and nonlinear adjustment and other is original.

  The data are

  X                       Y

  799.09857 257
  912.25256 641

  1026.00366 1516
  1137.92871 1118
  1253.43713 329

  Interesting.

  The initial default values assume all are NaN, which causes the LV calculate conjecture.  The default values for the parameter Bounds +/-Inf with the exception of the offset that are both zero. This, of course, forces the output zero offset.  It seems a strange fault, but they may have a good reason for it.

  Change the limits of compensation to something else translates the output being offset ~ 215 and the Center moves to ~ 1053.  These correspond the original result to 5 significant digits.

  Lynn

  

• Non-linear curve fit the model of reference file

  Hello.

  I use the VI of the non-linear curve adjustment in order to adapt the data. The reference to the fitting VI model I use is included in the attachment. You can see that I have a few constant wireline, like 4, 2500 and 1. I want to do this constant variables I'll change before each curve corresponds, because actually in my problem this variables I know before the adjustment and they are constantly changing, and for the moment this made VI just to test.

  The problem I have is that I can't enter the values of this variable to my main VI, where I also call the VI was nonlinear. The scheme of connection of refernce VI made must be changed in order to be recognized by the VI was nonlinear. I tried to use a table to transfer variables, but if I use one, it recognizes the variables as parameters of editing and he's trying to install as well in the adjustment process, and it gives me erroneous results.

  Any ideas how I can add the values of variables?

  Thank you very much.

  Kind regards

  Nikola comedy

  To provide additional data randomly in VI of model, you must use the entrance of 'data' (it is a variant and so can contain anything you want!). Just create any type of data you want (generally a cluster if there are several values of different data types) that contains all the values, convert them to a Variant in the main VI and the variant of wire to crimp her. In the model, you convert the variant return to data, to the constant help of cluster, such as defined in the main as VI 'type' (simply right click cluster in the main VI... wire Create constant... move the constant in VI of model). Now, to unbundle the different values and use them anywhere inside your model.

• apply restrictions for the non-linear curve fit

  Hello Forum users,.

  I am currently working on a VI control which is supposed to create a specific model of pressure inside a hollow tube to provide a test environment for pressure sensors. The details are many and complicated, so let's say I am sure that my formula to calculate this profile according to the pressures inside the hollow rings around this tube will work.

  To find the correct pressure for each ring values, I've linked to a model VI containing this form to Lev. - Mar algorithm (the non-linear curve adjustment) and let it run.

  Technically, there is no problem and Lev - Mar find values to adjust the function for the values (not perfectly sure, but close enough).

  The problem is, however, that, since the device, once suitable values for the positioning and size of the rings are found, must be built, the simulated pressure rings perhaps intersect not between them. To apply this rule, I added a check to my VI of model and if the values passed to Lev - Mar breaking the rules, the VI model gives a matrix of zeros to follow him (I tried an empty array, but that only leads to error messages).

  This solution did not work. Lev - Mar seems to ignore these cases always looks for values that break my rules (and if I put these values through my model VI, I get a matrix of zeros, as expected, so the audit seems to work).

  Perhaps I misunderstood the algorithm of Lev - Mar and it does not actually check each possible defined coefficients of finds.

  Is it possible to adapt to any function of a set of values while keeping the predefined boundary conditions?

  Oh, before I forget:

  I use LabVIEW version 8.2 in the Institute, because the workshop systems is not installed 8.5 for some reason any.

  Thanks in advance

  Thaliur

  Hi Thaliur,

  Thanks for posting on our forums.

  I understand your request you expect the algorithm to ignore a case to all zeros in the table. However, it is not implemented like this.

  Good news is, its source code can be edited and you could save your own personalized version of the algorithm of screws it is to you that you just add a check for a matrix of zeros or simply pass another parameter which indicates only a case of "broken rules". Then you would not have to continue the calculation.

  If I misunderstood your question, please clarify this. You can also post a code for further explanation, if you wish.

  Good luck with the project!

  Peter

• The non-linear curve fit lev mar problem

  Hi, I have a set of 10000 readings recorded every second. My goal to draw these vs time readings (1-10000 s) in logarithmic scale and adjust the exponential curve that results with my model equation: a1 * exp (t * b1) + a2 * exp (t * b2) + a3 * exp (t * b3) + a4 * exp (t * b4) and get the values of the coefficients (a1 to a4, b1 - b4). I changed the non-linear adjustment of lev - mar.vi according to my model. However, I ran into a problem.  I get the following: error-20041 occurred at LM.vi:5 to get on the curve of the NI_Gmath.lvlib:Nonlinear Possible reason (s): the system of equations can be solved because the input matrix is singular. I can't work on why I get this error. I enclose 3 files: the data file (values of Y), X = 1-10000; coating not get my model and vi vi.

  I'm using Labview 8

  I would appreciate your help and suggestions! Thank you very much in advance. ANU

  Hello

  @Jim-thank you very much... ur modified vi helped a lot... but a strange thing on the adjustment is that it depends a lot on the estimation of the coefficients... my model should have values of 'a' coeffs in the order of 10 ^-7 and 'b' should be higher around 10 ^-1. The initial proposal is amended the best coefficients made vary accordingly.

  I don't really know if this can b fixed... I enclose my vi.

  VI: - non - linear adjustment model, exponential branch.

  data - pol.txt

  I appreciate you all!

• The non-linear curve slope

  Hi all

  How can I get the slope of a particular point in the non-linear curve? I use Lev - Mar curve fitting is not linear.  The slope is to determine the dynamic resistance of the current-voltage curve of diode if dynamic resistance = 1/slope. Kindly help...

  
  

• Non-linear curve Fit error 20068?

  Trying to do a simple 3-exponential decay curve nonlinear.  I have a copy of this work in the other screws, but it doesn't seem to work in this VI.  I use "Scalablemultiexponentialdecay" of Altenbach as a VI/template model.  Data that I'm trying to adapt are a series simple decomposition RC, yes I realize that should not have 3 exponential components, it's just the model data.  I am able to adapt with the Fit exponential function built in to the Math palette, but which only works if the input bounds parameter is wired and with rational constraints.  However, I get an error on the adjustment of the non-linear curve that I understand not (photo attached) indicating that an INF or NaN is done in the settings.  I don't see where this is going...

  Any questions or help is appreciated.

  

  

  I thought so, only 0 s for the 2nd two exponentials.  But, if I replace all the guess seededes with the same as the simple exponential Installer, it converges without error.   I guess I didn't know it was that sensitive.  Thank you.

• coefficients variables semi in a non-linear curve fit

  Hi all

  I use a curved Lev - Mar not linear adjustment vi to fit a custom to my data function. The function is a set of Gaussian functions and an offset. I mean to constrain the width of one or more of the Gaussian curves in the function. I can do this by changing the values in the equation in the model description in the block diagram, but how to do this easily through the front?

  These width values will not be floated in the adjustment.

  Thank you!

  Unfortunately, the limited version was added in LabVIEW 8.5.  You could use the 'data' variant to pass the value of the stress sigma model and adjust the location and amplitude values. This means that your entry of Lev - Mar estimate does not include the values of sigma.  The value of sigma fixed wire entry "data".  Then depending on your model take data entry (type variant), cast to a value double precision and insert into the locations in your model formula.

  -Jim

• Non-linear curve fit (distribution of blackbody radiation)

  Hello

  In my measurements I would estimate the temperature from the spectra of light emitted through the Planck law of the distribution of the black body radiation. I tried to get my data with non-linear curve fit, but I encountered some problems:

  1.) function is not properly, because of the distribution of different adjusted data form and input data values.

  (2) when tracing distribution of Planck by using the best shape parameter, the plot is different from the theoretical distribution of given temperature. (My data comes from the source of temperature 3100K, best setting made is 1130K, but fit is different from the theoretical distribution of 1 130 K)

  

  When I get a few simple equations, everything works, so I'm not sure of what could be a problem.

  Many thanks for any advice.

  Ivan

  Quickly, giving once more on this, it seems to me that one of your constant if four orders of large magnitude.

  You get a very good fit with 3.74177E - 16 instead of 3.74177E-12, see picture. (You divide your theoretical curves by 10000, but you aren't in your formula!)

  

• Adjustment of the non-linear curve - maximum iterations exceeded (error-23026)

  Hello

  In my application, I use the curve non-linear adjustment VI (Levenberg-Marquardt) to adapt the data acquired continuously using a task DAQmx. Often in the course of the implementation of the instrument, the curves are not yet "adaptable" and max iterations set in the parameters of expiration is reached.

  It's OK but the problem is that it generates an error (-23026) that stops the execution of the VI.

  How can I ignore this error and continue to run the VI until the termination is controlled by the setting of tolerance?

  Kind regards

  Bernard

  Hi Bernard,.

  Need to wire the error output and handle the error programmatically.

• Sneak peek of the wave shape curve

  Hello

  I need one more glimpse of the actual waveform curve comes to know the exact position where I am, when I zoom in and out of the chart with a cursor position for measurement purposes. Could someone help me please how to do this. Thanks in advance

  Concerning

  Julien

  Julien wrote:

  Could you please save on Labview 10 and post again

  Of course, you can go.

• I need to create a curved with type text box that heal and return to the next line in the form of curved text. How do I do that?

  I need to create a curved with type text box that heal and return to the next line in the form of curved text. How do I do that?

  1. Draw a set of concentric half circles also spaced, stacked so that the outermost is the most remote.
  2. Use the text tool to add text to the outermost path, thus creating a PathType object.
  3. Select all the paths. Type > threaded text > create.
  4. Text tool: click at the end of the text in the object of PathType. Continue typing.

  

  > If I do that it will not type more.

  A Warp effect is a direct effect. When it is applied to the type of objects, they are still editable text. The chain will deform, however, the text also, not only the paths to which it is attached. Sometimes you want that, sometimes you don't have.

  JET

• Somehow my basic develop settings have disappeared - what is between the histogram and curve is missing. Help!

  I have no idea what happened, but I don't have development options under the histogram and above the tone curve - so not only increase the white balance, no sliding bars to actually adjust my photo. Help, please!

  Hold the cursor over a black area just above the area of curves along the side of R, then select BASIC, OR ANY OF CHOICE.

  Vince

• Adding points to the adjustment layer curves in PsCS6 broken?

  In CS3, CS4, and CS5, I was able to:

  b add a point (corresponding to the position of the eyedropper on the image) by Ctrl + click RGB composite curve; and

  b add a point (while wearing on the RGB composite curve) to each of the curves by Ctrl + Shift + click on channel red, green and blue.

  No approach seems to work in my CS6 (PsCs6 x 64 last updated, in Win 7 x 64).

  Is a kind soul able to tell me the correct key combination to achieve the desired result, or is there really a problem with CS6?

  Post edited by: hienromaric

  It should be documented here:

  https://helpx.Adobe.com/Photoshop/using/curves-adjustment.html

  Most of the above is the on image setting target adjustment (tool) must be enabled

  (the hand symbol with arrows in the properties panel)

  then you click on the image (no modifier key) to add a point to the composite line and Ctrl + Shift to add points to the red, green and blue channels.