Introduction to the tutorial of curve fitting - find a function

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

  As stated in my first question, I asked yesterday I'm new to labview and I always work in the curve editing tutorial, but I am now up to the non-linear section (although I jumped the polynomial stuff for now).  So my question now to do the with the vi illustrated in Figure 14 of the Introduction to the tutorial Curve Fitting.

  My problem this time has do with graphic design for data non-linear Gaussian and adapt.  Looks like it gets its data from a cluster of some sort which is itself drawn to clusters separate construction.  The problem is that I can't find the appropriate function of cluster, which will result in the production of a graph.  I had a test using a variety of different cluster functions and also have a look to try to use a matrix function and none of them work.  Now, an assumption that I did is also that the graph is of the form XY (and not a waveform graph).

  Note that I am aware that part of the problem could be my lack of experience in coding using labview, as I've attached the vi that I worked on.

  I'm using labview 8.6.

  Thanks again for any help.

  Do not use the function you are using.  Use the cluster on each plort bundle, then build the table of these 2 groups.

  To the Subvi, you right-click the entry that caused the broken arrow and choose create constant.

  Whenever you have a problem trying to find the right data type into a Subvi.  Do a right click, create constant.  Now, you will have a default constant of the correct data type that you can modify as needed.

  

• 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

• Need help with the non-linear curve - fit

  Hello

  "I enclose you a VI that calls the function of nonlinear smoothing" Lev - Mar "with two slightly different formulas.

  On my machine (Win7, LV2011) adjustment is a straight line when bool example FP is set to FALSE.

  This is expected behavior?

  Is it possible to get a good fit, with the coefficient of 0.97 and _without_ increase in the number of points?

  Thanks in advance!

  I've just implemented the formula to the fitting VI.  I did not review the calculation you did for "raw" data

  Review: The first value of x is equal to zero. To get a phase shift of ~pi/2 a good first guess for c is 1.57.  With a value close to that, it gives a good fit for each choice of c.

  

  Lynn

• 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!

• 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.

• 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

  

• I JUST DOWNLOAD THE CC ON MY DESKTOP N HAVE NO IDEA WHERE TO START PHOTO EDITING IT S LITTLE DIFFERENT OF MY ITEM 12 NEED HELP TO FIND THE TUTORIAL THANK YOU A.S.A.P.

  I JUST DOWNLOAD THE CC ON MY DESKTOP N HAVE NO IDEA WHERE TO START PHOTO EDITING IT S LITTLE DIFFERENT OF MY ITEM 12 NEED HELP TO FIND THE TUTORIAL THANK YOU A.S.A.P.

  Start with the tutorials in the Welcome window to start and takes a course from a site like Lynda.com.

• Problem of Nonlinear Curve fit: Lev - Mar

  Hello, I am trying to use lev - mar to fit my data. I think that lev - mar is suitable for my non-linear data of the diode I - V curve. How to connect the input of the VI of lev - mar? What should I put in the data / initial settings / covariance? I've seen examples in the labview, but still can't find the solution.

  Suggest you start here: Introduction to the adjustment of the curve http://www.ni.com/white-paper/7669/en/

• Is there a phone rep who can help me get my profile on my new computer? I think I did OK for the tutorial, but now it does not work

  I had to buy a new computer as my last one had problems. I backed up what I think is all of my files on an external hard drive and moved them to the new computer but Thunderbird does not open. So I re downloaded Thunderbird and followed the tutorial on copying and pasting the old profile in the profile folder and now Thunderbrid (I think) will not open.

  Thunderbird profile cannot be loaded. It may be missing or inaccessible.
  

  So I put everything in the trash and re downloaded the program, and I still get the same error (I however wouldn't be the case that I was starting from scratch).

  In a little over my head. Any help?

  Try this method to import emails.
  addon ImportExporttools:

  • https://addons.Mozilla.org/en-us/Thunderbird/addon/ImportExportTools/

  Download the as file and save it to your ex: desktop

  In Thunderbird

  • Tools > Addons or Menu icon > Addons
  • Click the gear icon and select "install the addon from file".
  • Find the downloaded as file and click 'open '.
  • You may have to restart Thunderbird.

  To import an mbox file (all messages are stored in Thunderbird mbox files)
  Right click on the email account
  Select: ImportExporttools > import a mbox file
  Select: directly import one or more mbox files
  Search for the file and click 'open '.

• 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.

• Curve fitting only part of a waveform

  I take a few data of an Oscilloscope and I need to make an adjustment to the curve.  As you can see it on the data in the Appendix data starts at 0 and ends a 10-6.  I want to just curved put on the part of the 5th-6 to 10-6.   That's what I tried

  (1) I take the waveform and use a "waveform components get."  Then I take the data Y and remove the first half of the data in the table.  Then I use a wave 'building' and put in the new data of Y and data from dt to make the NEW waveform.  I then put in for the VI Curve Fitting Express.  This works well for the slope, but of course the point of intersection is disabled because data that was in the 5-6 are now 0.  And 10th-6 data are now at 5-6 because I have stripped the first 5-6 data and reconstructed the waveform.   I thought I could use the 't0' value in the 'Build' wave to set the beginning of the NEW waveform at 5th and 6, but it seems that the "t0" is only for a timestamp (this is a calendar of data).

  (2) I thought to convert the waveform in X and is given because it is easy to transfer data from X by just add 5-6 each value in table X.  But then he would not enter the Curve Fitting Express VI.

  (3) I thought to use the "places" of the curve fitting Express VI entry, but I could not really get that to work.

  Thanks for any help.

  Away from the express VI and the Plains tools operating on simple table data. Many of the fitting screw (for example a linear adjustment) have an entry 'weight', then the value of weight zero for the data outside of the desired range. You can also simply take a subset before mounting.

• Bad display-how can I reduce the size of the web page to fit my acer notebook the screen is big

  My Acer Aspire used to automatically adjust the web page to fit my smaller screen, but it seems to have stopped working and I can't find how to fix the problem.

  [Moved from comments]

  In Internet explorer, you can use these shortcuts.
  Other browsers are similar.

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• 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!)