Non-linear voltage with current variance

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• Error-20003 of curve non linear adjustment LM with a VI curve as a good model

  Hello

  I was stuck for a while now, by an error when I use the non-linear curve mount LM with a VI as the model curve adjustment. The code error is-20003, and occurs in the "LM get new coefficients ' vi and analysis, said"the number of samples must be > 0 ". I checked a number of things, but I can't get rid of it. The VI is quite simple: it uses a database of three sets of numbers (or ghosts) and it aims to adjust a curve that is the sum of these three spectra to determine the multiplicative coefficient associated with each spectrum. The code is attached to this message, thank you so much for any input!

  Looks like your model function has default data stored in the output of f'(x,a).  Try to empty the table (be sure to "Save as default" after emptying) and run again.  This solved the problem on my machine.

  Apart from this specific error, it seems that your model is linear in the spectrum of the molecule, so maybe using Fit.vi linear General is a better match for your problem?  The two algorithms give the same results on my machine.

  -Jim

• 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...

  
  

• 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

• How can I make measurements on a node or a non-linear element in a subckt

  I'm trying to do non-linear measures (especially the voltage) on the various elements that are in a secondary circuit of my high level design.  Is there anyway that I can select a particular node to perform these measurements on?

  Hello

  You can do in the measure dialog. Once you have the winodw dialogue measure, there will be three dots next to the measuring element right and then you can click on it and a new window opens. In the new window, click on your desired sub-channel and click on the button on the top and then select the node you want to your measurement to make. I've attached a photo showing the three steps that we discussed.

  

  I hope that helps!

• How to calculate the equation of dataset using 'Fitting VI' (non-linear or polynomial fit)?

  I have the datasheet of a NTC (thermistor negative Coefficient) and I want to calculate the most approximate equation

  that describes its behavior. The table has values of temperature and resistance. If the resistance of the NTC varies according to the temperature it detects. I tried the following:

  -Excel: polynomial adjustment

  -Maple: polynomial adjustment

  -LabVIEW: Polynomial Fit.vi

  I've been doing equations with a not very good approximate parameteres. I suspect that this method 'Polynomial FIT' it is not the best method for this type of data/equation (being a non-linear equation).

  So is - that someone has used the non-linear Fit.vi matching the behavior of a dataset object? If so, can you explain how this VI... I would really appreciate it.

  Thanks in advance and I will wait for your reply.

  
  

• 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.

• non-linear system Solver more equations than unknowns

  Is it possible to solve a nonlinear system with more equations than unknowns in LabView. I do a triangulation and data from several sensors, so I'm able to write 6 equations in order to get the 3 coordinates (x, y, z) as a solution. In LabView, I was able only to solve a system of 3 equations with this 3 unknowns, but I would use the set of 6 equations in order to obtain a more accurate solution, given that some measures can be noisy.

  Thanks in advance

  You can use the non-linear curve code to solve this problem. Consider the following system:

  3XY + y - z = 12

  yx + x ^ 2 + z = 12

  x - y - z = - 2

  Arrange to get 0 right side. x, y and z are the paramneters to be in shape. The entrance to the curved Fti.vi Y non linear will be an array of three zeros. Initial settings will be an array of three values, for example [1 1 1]. An example is attached.

  -Jim

• 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 shape VI don't, get error-20068

  Hi, I have a problem of raw data to a formula of mounting. The formula is f (x) = - ax + b + c (x/d) ^ e. I use the non-linear curve Fit VI, Lev - Mar: the formula string. I'm able to calculate 4 5 parameters (a, b, c and d). I can't calculate, but it should be around 10. When you run the VI, it gives me "error-20068 occurred at NI_Gmath.lvib:LM get new coefficients.vi:1. " "Analysis: input parameters has at least one element that is Inf, NaN, DBL_MAX or DBL_MIN"

  It is tracing the equation based on the initial settings without actually finding the best adjustment of the parameters. I also tried using the VI version to create the formula, but it gives me the same error. What can I do to avoid this error? I have attached the vi and a data file.

  

  Some of your top X values are negative. Remove them and things will work fine.

  (You get a negative signal for the exponentiation, which is allowed if the entry is complex or the exponent is an integer. This isn't the case here, where the exponent is not an integer. The exponent is an integer in the first function call, but not more once, trying to calculate the partial derivatives of the model. Try with a hypothesis of 9.9 instead of 10, and it will fail immediately)

• 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.

  

• 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!

• calculate the symmetrical components of voltage and current

  Hi all. I work on the calculation of symmetrical components of voltage and current in Labview. I have included the relationship between the symmetrical components and sequence as photo 1 voltage. I'm going to use this calculation for several times, so I wonder if anyone has some ideas far better bc I wired just so much together to realize the expression. It seems aweful. Any suggestion? as built-in function to achieve this function? Thank you

  Let's take a look on your form (you don't say what is complex, etc, so modify as needed)

  

  For example, here is how you create the matrix A to an alpha given.

  

  Similarly, you can create A ^(-1) matrix (your definition of A and A ^(-1) seem incompatible, otherwise you could just pick matrix inverse of A). After that, you can multiply with you V123 vector using AxB.

• Chroma DC power supply RS232 communication (read problem of over-voltage and current)

  Dear all.

  I chroma programmable DC power. Based on the programming of the Instrument manual I develop using RS232 communication. Based on the program I can set the voltage, current, over-current protection, protection against overvoltages and make IT / OFF out put supply perfectly.

  But I have to read the measured values of the output power as current and voltage. Measured applications are the voltage and current of the output of the power supply. My problem is two of them read at the same time. Currently, the reading is only voaltge or current (if the first request is v? it is voltage read out but no reading for the current) and if the first request is CURR? the reading for the current, but not for VOLT? The status message is OK, even if it is to read values.

  Thanks in advance

  What I see in your program, it's that you do not use the stop for reading character. For your writing, you do the hard with all these concantanate string functions. You can set the stop character for all entries with a node unique propert - "ASRL end Out.

• 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!)