Levenberg Marquardt adjustment: problem of formula

Similar Questions

• How to track the progress of Levenberg-Marquardt

  Hi all

  My Levenberg-Marquardt works perfectly, but one iteration takes quite long, about 5 seconds, as expected from the complexity of my problem (~ 50 parameters fit).

  Question: How to display the current number of interaction in the main program, for the user to know that it is still ongoing?

  (My solution so far is to put a probe in the Levenberg-Marquardt subroutine provided on this 'i', which is the current interation. "But it's not easy to use).

  Thanks & best regards!

  Peter, LMU Munich, Germany

  You can use your model VI to increment a counter that appears elsewhere. If your model compute partial derivatives, then there will be only one call per iteration LM model VI plus 1 for the estimate.  If you are not calculating the partial derivatives LM then uses central difference method to calculate them.  This means function by iteration of LM 3 calls, plus 3 for the estimate.

  -Jim

• Levenberg-Marquardt optimization question

  Hello

  I am trying to use the Levenberg-Marquardt algorithm, using a technique of optimization error percentage instead of the technique of the absolute error. AFAIK the Levenberg Marquardt in Labview algorithm uses the technique of the absolute error (i.e. Y - f(x)) when calculating on the errors. How can I change this option to use the technique of percentage error, when the error = [(Y - f(x)) / y] * 100? I changed the calculation of the error in the algorithm to calculate the error in this way, but the results were not satisfactory. I wonder if I forget something or there at - it much more to what meets the eye? I know that in other programs like Mathematica you can choose how you want the error calculated, but I do not see this option in the Labview vi. Any help appreciated.

  Thank you

  LMS

  Additional information:

  I'm using Labview version 8.2

  I changed the Subvi ABX to calculate the error differently. The ABX vi contains a Subvi called gradient and function of LM. The output of this Subvi calculates better suited like Y - the error. I changed this calculation to be [((ajustement Y-meilleur) / y) * 100] to obtain the percentage of error instead. This affects alpha, beta and chisqr. I think I may need to make other changes to the algorithm to implement the technique of error in percentage but I don't know what changes to make. The results that I have received the above changes were worse than the results I got from the method of the absolute error (error = Y – the better suited). This should not be the case. I implement the VI of the Levenberg-Marquardt algorithm format and not the string of the formula. Any help appreciated.

  Thank you

  LMS

  Hi LMS.

  I don't know if I understand.

  However, as the Lev - Mar algorithm calculates Y - f (x). If you divide that result by the best linear fit (Y) and multiply by 100. This will give you your desired effect.

  I hope this helps you.

• Adjustment of curve using Levenberg-Marquardt algorithm

  Hi all

  Thank you for my request answered in the last post. One thing I like about Labview is its ability to allow complex models to be fitted to experimental data with so much ease. I have been using the L - M unconstrained editing for some time. However, there is a question to which I thought I would like to be answered by Labview professional themselves.

  When the curve adjustment is completed, the algorithm always has the minimum value for a reverse parameter. for example. Suppose that a parameter X is found to have a value of 0.8 after editing by l.-m. algorithm. However in principle several orders of values are possible for x. for example is not a sensitive parameter in the main equation so it can have values of 1000 or 400, or 60, 1. In this scenario the algorithm will always give an answer like X = 1; This is the minimum solution?

  See you soon,.

  Navneet

  Navneet,

  Implementation of Lev - Mar in LabVIEW does not explicitly attempt to diminish the importance of any parameter.  If the parameter has as little impact on the distance between the data and the best curve fit, then it will change according to the gradient of the problem.  If the parameter does not affect the distance, so that you can get a linear solver error indicating a deficiency in a row.

  You can detect this behavior by using the Intervals.vi to mount curve nonlinear.  An interval that is very large compared to the other parameters would indicate a low dependence on this setting.

  -Jim

• Adjustment of Levenberg-Marquardt tweaks

  Hello

  I have two questions about the non-linear curve fit LM VI:

  (1) does anyone know why after one iteration successfully the lambda value is multiplied by 0.4 instead of 0.1 as in the implementation of the standard (i.e. Numerical Recipes)? This factor has an influence on the speed of the adjustment?

  (2) is it possible to use analytical derivatives to speed the evaluation of the slope and the Hessian of Chi-square?

  Thank you

  Bernard

  (1) maybe it's so nobody is accusing them of use directly the NR without attribution.  That the value is just an empirical assumption, so there is nothing too magical about 0.1 or 0.4 (better to be less than 1).  As you have found where this value is used (not too hard), I suggest that you experience in the changing of 0.1 or 0.2 or 0.5 and see if that makes a difference.  Let me know, I have not tried.  When I implemented the systematic NR in LV, I used 0.1 and it worked, and when I use the LV routine with 0.4 it still works.

  (2) If you select f(x,a) is a VI a slot - VI is used to calculate the values of service, you can also return the analytical derivatives.  This can save time and reduce rounding error, and I recommend warmly when possible.

• Problems with formulas IF nested in figures

  Been to my local apple store who put a request for the Apple Business team to ring me (but that was 4 days ago now!)

  I'm trying to write a formula to decide if a number in a cell would amount to a failure, Pass, merit or Distinction (based on value)

  I came with all sorts of scenarios - the latter being to throw a rice paddy and a coffee because I can't get my head around it? Is anyone able to help me?

  39 or below = Fail

  40-59 = pass

  60-79 = deserves

  80 + = distinction

  I also then of course need to copy the formula to the bottom of the worksheet.  I hope if anyone can help me with this the second problem that I have is fixable too as I may be able to sort me!

  Thanks for any help you can give

  This should be a good start:

  

  Create a second table (on the right, called "Award"), where the first line is a heading row.

  to make a header line, select the first line, and then click the context menu display arrow in the row heading (the number '1' on the far left):

  Note these images are converted to the first line of the table on the left (but the concept is still the same for the table to the right)

  

  

  Here is the content for the price table:

  Grade	Price
  0	IN CASE OF FAILURE
  40	PASS
  60	MERIT
  80	DISTINCTION

  in the data table where you want to convert a numeric value to a scholarship name:

  

  Select cell C2, then type (or copy and paste it here) the formula:

  = VLOOKUP(B2, Award::A:B, 2)

  shorthand is

  C2 = VLOOKUP (B2, Award::A:B, 2)

  Select cell C2, copy

  Select cells C2 at the end of the C column (or), paste

  

• Problem with formula node

  Hello

  I'm using LabVIEW 2012 and there seems to be a problem with the node of the formula. The output of a simple no operation is not correct.

  I have an input U8, whose value is 255. I apply a no operation (a = ~ a and the value returned by the formula node is also 255.)

  Is this a bug in the node or there at - it another way to calculate the bit DO NOT level?

  Thank you

  Ritesh

  You must use the function or exclusive.  So what you really need, is:

  a = a ^ 0xFF

  EDIT: Dig even more, it is called a 'top-up bit.  I consider cela a bug.  I see the same thing with 2011.

• Automatic adjustment problem

  Hello!

  I scoured the forums for troubleshooting on this issue, but I have not found someone with the same problem as me.

  I have a problem with my Dell U2311H monitor - this is just pure black. At first I thought there could be something wrong with my cable signal, so I just have to move on to a new (DVI) when it does not, I thought it might be a problem with my DVI out and changed to VGA. Still the same problem. The strange thing is, that my other moniter connected to my computer (Philips TV) works perfectly fine, except for one small detail. I used the TV to play a game that I play every day, and he has always displayed the game in 16 / 9, but from when my screen has stopped working, the TV is now show the same game in 4:3. This leads me to believe that there could be a problem with my graphics card, but I don't know what kind of problem that would be. The power calbe works as well.

  I have however noticed that whenever I have disconnect or connect cables or change the settings for screen resolution, my Dell monitor suddenly comes alive again, but only for a second or two, while displaying the message 'Current Auto adjustment' and then turn black again. Just browsing the forums I found a few people with the same problem, but they seem to all run Windows XP because they speak by pressing the 'computer turn off the power"- button and pressing a button on the screen. Their problem also seems that 'the current auto adjustment' flashes on the display, and it works very well except that.

  So if anyone has a solution that they would be my hero and save a poor student does not consume $ 200 on a new screen :)

  This is just to conclude, the things I've tried:

  -Switching cables DVI, VGA and power cable

  -Check that all cables are properly connected

  -Downloaded the latest drivers for my graphics card (apparently there aren't any for my monitor)

  -Restarted my computer (obviously)

  -Unplugged and re plugged my graphics card

  -Lower the resolution on the screen

  -Unplugged my TV (HDMI input)

  I hope someone can help me!

  It is not a problem with the source of the video signal (desktop computer, HDTV, etc.). If you have another monitor, you can check this. The problem is with your monitor. There are two parts that are required to produce the light coming through the screen, the CRT, which is a bit like a fluorescent bulb, and the Council of the inverter that powers the light bulb.

  You could look for a local store that diagnoses and repairs monitors. Generally, parts are pretty cheap.

• Levenberg Marquardt

  
  
  

• Reference of Levenberg Marquardt

  Hi all

  I implemented the LMA succesfully in my thesis and calculated the necessary uncertanities descrobe by Jim and Altenbach method in an another messages. Jim the guy from the DSP has also shown using NIST standards that the multiplication of the matrix of final covariance with the MSE provides good estimates of the variances. I wanted to refer to it in my thesis and I was wondering if there is any report or document published someone made this list.

  Thank you

  (Kyle, you two last links are broken.)

  Chapter 15 digital revenue has useful information.

• Brightness adjustment problem

  All of a sudden, I can't change my screen with f2 and f3 brightness and nor in the Panel. Is there a new driver I need to install?

  My product number is > G6S71UA #ABA

  Hello

  Try to use Recovery Manager to reinstall your original Intel - the procedure graphics driver to use the Recovery Manager to reinstall the drivers and software is detailed in the document at the link below.

  Recovery Manager - Windows 8.

  After reinstalling, restart the laptop.

  Kind regards

  DP - K

• Field - LENGTH href image adjustment problem

  I have try this simple code to define a href of an Image/ImageField object that does not work.

  Image1.value.image.href = 'http://www.adobe.com/ubi/globalnav/include/adobe-lq.png';

  Am I missing something?

  Nith

  The only way you will get th ephotos to day after the form has been returned is by delivering the content of the picture in a web service call. You can have the content image base64 encoded and put in a string in the WS call (in output). Then you can bind this production line to the CImage th field and it will work. You can not Acrobat/Reader recover images once the form has been made. This has been disabled for reasons of security from version 8 I think.

  Paul

• The development of adjustment problems

  When you use focusManager.setFocus (txtfield) in a module, it seems to lose his accent.

  I don't know why this happens, since I put in focus after the module was created. Here is the code from my module:

  <?xml version="1.0" encoding="utf-8"?>
  <mx:Module 
       xmlns:mx="http://www.adobe.com/2006/mxml" 
       layout="absolute"
       creationComplete="mdl_init()"
  >
       <mx:RemoteObject
            id="LoginRemote"
            destination="login"
            showBusyCursor="true"
       >
             <mx:method name="sign_in" result="signin_handle(event)" />
             <mx:method name="sign_out" result="signout_handle(event)" />
       </mx:RemoteObject>
       <mx:Script>
            <![CDATA[
                 import mx.rpc.events.FaultEvent;
                 import mx.utils.ArrayUtil;
                 import mx.rpc.events.ResultEvent;
                 import mx.controls.Alert;
                 import com.brassworks.ValueObjects.CurrentUserVO;
                 import mx.events.VideoEvent;
                 
                 [Bindable]
                 private var this_user:CurrentUserVO = new CurrentUserVO();
                 
                 private function mdl_init():void
                 {
                      focusManager.setFocus(txt_username);
                 }
                 
                 private function signin_handle(event:ResultEvent):void
                 {
                           this_user = event.result as CurrentUserVO;
                           if (this_user.token == null) {Alert.show("Supplied login credentials are not valid. Please try again.");}
                           else
                           {
                                this.parentApplication.setUser(this.this_user);
                           }
                 }
  
                 private function signout_handle(event:ResultEvent):void
                 {
                      
                 }
                 
                 private function sign_in(event:Event):void
                 {
                      //Alert.show(txt_name.text + "|" + txt_password.text);
                      LoginRemote.sign_in(txt_username.text, txt_password.text);
                 }
  
                 private function sign_out(event:Event):void
                 {
                      
                 }
                 
                 private function show_error(error:Error, s_function:String):void
                 {
                      Alert.show("Method:" + s_function + "\nName: " + error.name + "\nID: " + error.errorID + "\nMessage: " + error.message + "\nStack Trace: " + error.getStackTrace() + "\nError: " + error.toString());
                 }
                 
                 private function handleFault(event:FaultEvent):void
                 {
                      Alert.show(event.fault.faultDetail, event.fault.faultString);
                 }
  
            ]]>
       </mx:Script>
       <mx:Panel
            id="pnl_signin"
            title="Sign In"
            horizontalAlign="center"
            verticalAlign="middle"
       >
            <mx:Form
                 id="frm_signin"
                 cornerRadius="5"
                 defaultButton="{btn_signin}"
            >
                 <mx:FormItem
                      id="fi_username"
                      label="Username:"
                 >
                      <mx:TextInput
                           id="txt_username"
                      />
                 </mx:FormItem>
                 <mx:FormItem
                      id="fi_password"
                      label="Password:"
                 >
                      <mx:TextInput
                           id="txt_password"
                           displayAsPassword="true"
                      />
                 </mx:FormItem>
            </mx:Form>
            <mx:ControlBar>
                 <mx:LinkButton
                      id="lnk_request_password"
                      label="Forgot your password?"
                      click="currentState='RequestPassword'"
                 />
                 <mx:Spacer
                      id="spc_spacer" 
                      width="100%"
                 />
                 <mx:Button
                      id="btn_signin"
                      label="Sign In"
                      click="sign_in(event)"
                 />
            </mx:ControlBar>
       </mx:Panel>
       <mx:states>
            <mx:State
                 name="RequestPassword"
            >
                 <mx:SetProperty
                      target="{pnl_signin}"
                      name="title"
                      value="Request New Password"
                 />
                 <mx:SetProperty
                      target="{btn_signin}"
                      name="label"
                      value="Submit Request"
                 />
                 <mx:RemoveChild
                      target="{lnk_request_password}"
                 />
                 <mx:RemoveChild
                      target="{fi_password}"
                 />
                 <mx:AddChild
                      relativeTo="{spc_spacer}"
                      position="before"
                 >
                      <mx:target>
                           <mx:LinkButton
                                id="lnk_sign_in"
                                label="Return to Sign In form."
                                click="currentState=''"
                           />
                      </mx:target>
                 </mx:AddChild>
            </mx:State>
       </mx:states>
       
       <mx:transitions>
            <mx:Transition
                 fromState="*"
                 toState="*"
            >
                 <mx:Parallel
                      id="trn_default"
                      targets="{['RequestPassword']}"
                 >
                      <mx:Fade
                           alphaFrom="0.0"
                           alphaTo="1.0"
                      />
                 </mx:Parallel>
            </mx:Transition>
       </mx:transitions>
  </mx:Module>
  

  Ideas?

  Thank you!

  Mike

  Hi, there is a constraint between flash player and web browsers for it to get the focus in any object inside the flash player, you must manually click inside the flash player instance.

• Problem of Fit 2D Gaussian.

  I have a 2d Gaussian curve fitting problems.

  I have a set of data: with 3 columns and rows of N. For example

  x y intensity.

  ..   ..      ..

  N is the same for all 3 columns. I'm trying to create a plot intensity out of these data and adapt a 2D Gaussian to it.

  I tried to do a polynomial interpolation of the intensity of data on the x - go and carry out a plot of intensity (do not know if there is a better way to do it! Please Suggest if there is nothing else.).

  Then I use the Levenberg-Marquardt method to adapt to these data. For some reason, it does not any iteration estimation. The best value of adjustment is the same as the estimate. There is shoing error: NI_Gmath.lvlib:LM is coefficients.vi:1 again. (see attached screws)

  Can someone help me with this!

  Thank you.

  OK, I quickly changed my old example and it seems very easily mount your raw data. See attached (LV2010). Modify if needed.

  (Note that I set the width as 'width at half the height', your definition may differ.)

  

• 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.