Comments on: How did I get an algebraic loop error, when the diagnostic was set to warning? http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/ This blog is about Simulink. Tue, 14 Feb 2012 17:41:30 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Asier http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1661 Asier Thu, 29 Dec 2011 14:53:27 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1661 I've just solved an algebraic loop by changing tehe name of a block from "Antialiasing" to "Subsystem". Answer to that? It's just curiosity. I think i'll neveer understand this program... I’ve just solved an algebraic loop by changing tehe name of a block from “Antialiasing” to “Subsystem”. Answer to that? It’s just curiosity. I think i’ll neveer understand this program…

]]> By: Mahmoud Moussa http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1565 Mahmoud Moussa Fri, 23 Sep 2011 13:16:33 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1565 The problem in my point of view was solved easily by putting "unit delay" inside the loop Simulink library browser-->Discrete-->unit delay After doing that, no problem message appeared Try this, may be it can help All the best Mahmoud Moussa The problem in my point of view was solved easily by putting “unit delay” inside the loop

Simulink library browser–>Discrete–>unit delay

After doing that, no problem message appeared
Try this, may be it can help

All the best
Mahmoud Moussa

]]> By: gladis suarez http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1453 gladis suarez Fri, 29 Apr 2011 23:39:28 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-1453 hello, I have a program which in the simulink matlab 2007 run well , but when I want run it in the simulink matlab 2008 the simulations stops with the error: Trouble solving algebraic loop containing 'test1_L/Fuel cell/transfortation' at time 0. Stopping simulation. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances). how I can solve this problem, thanks hello, I have a program which in the simulink matlab 2007 run well , but when I want run it in the simulink matlab 2008 the simulations stops with the error: Trouble solving algebraic loop containing ‘test1_L/Fuel cell/transfortation’ at time 0. Stopping simulation. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances). how I can solve this problem, thanks

]]> By: Seth http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-965 Seth Tue, 02 Feb 2010 03:38:43 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-965 I am not sure of your implementation of the D flip flop, and I am not sure how it is causing an algebraic loop error. There is flip flop library in the Simulink Extras library. You may be able to try using that. I am not sure of your implementation of the D flip flop, and I am not sure how it is causing an algebraic loop error. There is flip flop library in the Simulink Extras library. You may be able to try using that.

]]> By: sisir kalita http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-952 sisir kalita Thu, 21 Jan 2010 06:50:00 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-952 how D flip flop can be designed in simulink... we r facing problem while simuliting using NAND gate as it shows algebric loop error.. how D flip flop can be designed in simulink… we r facing problem while simuliting using NAND gate as it shows algebric loop error..

]]> By: Mohamamd http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-899 Mohamamd Wed, 18 Nov 2009 15:23:38 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-899 Hi Suth, I try to simulate a load tap-changing transformer in simulink but its control part has to be impelented in stateflow, I did it but simulating the system I get this error message, Trouble solving algebraic loop containing 'handy_ltc23/Three-Phase OLTC Regulating Transformer/Chart' at time 5.033333333333321. Stopping simulation. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances) The point is that I have to use stateflow for its control part and I can't refuse that, inside the stateflow chart I just want to update a variable one unit every 4 sec, can Not I do it? I'll be very grateful if you give me a key regards Mohamamd Hi Suth,
I try to simulate a load tap-changing transformer in simulink but its control part has to be impelented in stateflow, I did it but simulating the system I get this error message,
Trouble solving algebraic loop containing ‘handy_ltc23/Three-Phase OLTC Regulating Transformer/Chart’ at time 5.033333333333321. Stopping simulation. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)
The point is that I have to use stateflow for its control part and I can’t refuse that, inside the stateflow chart I just want to update a variable one unit every 4 sec, can Not I do it?
I’ll be very grateful if you give me a key
regards
Mohamamd

]]> By: samad http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-859 samad Wed, 23 Sep 2009 08:53:44 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-859 hi javad if you have any problem please write me with my Email. I hope that i can help you with your mat/simu problem. hi javad
if you have any problem please write me with my Email.
I hope that i can help you with your mat/simu problem.

]]> By: javadaein http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-790 javadaein Tue, 30 Jun 2009 13:04:30 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-790 unfortunately mathworks can not be accessed in iran. I dont know why mathworks guys do that but I can't solve my simulink related problems. unfortunately mathworks can not be accessed in iran. I dont know why mathworks guys do that but I can’t solve my simulink related problems.

]]> By: Amin http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-490 Amin Thu, 14 Aug 2008 18:28:23 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-490 Hi Seth! I'm very confused. in the Simulink document http://www.mathworks.com/access/helpdesk/help/toolbox/simulink/ug/f7-8243.html#f7-19688 solving simple algebraic loops with The Algebraic Constraint block and find z1 = 0, z2 = 1. i solve this example without this block and find z1 = -1, z2 = 1; Which answer is correct? Hi Seth!
I’m very confused. in the Simulink document
http://www.mathworks.com/access/helpdesk/help/toolbox/simulink/ug/f7-8243.html#f7-19688
solving simple algebraic loops with The Algebraic Constraint block and find z1 = 0, z2 = 1.
i solve this example without this block and find z1 = -1, z2 = 1;
Which answer is correct?

]]> By: Seth http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-428 Seth Fri, 18 Jul 2008 03:12:41 +0000 http://blogs.mathworks.com/seth/2008/07/03/how-did-i-get-an-algebraic-loop-error-when-the-diagnostic-was-set-to-warning/#comment-428 @Pedro - Simulink does uses Newton's method to perform a search for the solution. If you have trouble getting it to converge, note the algebraic variable, and place an IC block (initial condition) at the output port of that block. You can then provide an initial guess for the solver, and may improve your results. The result from the last solution is used as the initial guess of the next step, and should allow the model to move forward in time. Good luck! @Paul J - Thanks for the rant. You are right... the second type of algebraic loop are the ones that cause me the most frustration too. In some cases I find conflicting specifications are to blame. If a subsystem is marked as Atomic, Simulink must be able to compute all of the outputs at the same time. If there are dependencies on inputs, and those have a direct feed-through path back to the outputs, there is a sorting problem to be handled. Thanks for contributing to the discussion! @Pedro – Simulink does uses Newton’s method to perform a search for the solution. If you have trouble getting it to converge, note the algebraic variable, and place an IC block (initial condition) at the output port of that block. You can then provide an initial guess for the solver, and may improve your results. The result from the last solution is used as the initial guess of the next step, and should allow the model to move forward in time. Good luck!

@Paul J – Thanks for the rant. You are right… the second type of algebraic loop are the ones that cause me the most frustration too. In some cases I find conflicting specifications are to blame. If a subsystem is marked as Atomic, Simulink must be able to compute all of the outputs at the same time. If there are dependencies on inputs, and those have a direct feed-through path back to the outputs, there is a sorting problem to be handled. Thanks for contributing to the discussion!

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