Why am I receiving error messages about singularities in my Simulink model?

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I am receiving the following error messages about singularities in my Simulink model:
Derivative of block at time is Inf of NaN. Stopping Simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances.)
I have tried reducing the step size and adjusting tolerances, but I still receive this error message. I have also tried changing solvers, some solvers will just get to one point of the simulation, and hang.

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 14 Apr 2011
This message may be caused by a singularity in your system. One situation where this may occur is if the values of your states differ by a large magnitude. If this is the case, the Simulink solver will have a hard time resolving your step size within the error tolerance as it attempts to "bounce" back and forth between the states.
To check if this is the case:
1. Return the states of your system as follows-
a) In the model editor go to Simulation-> Configuration Parameters
b) Select Data Import/Export, in the 'Save to Workspace' field, check 'States' to log the states as output
2. Run the simulation.
3. Plot:
plot(tout,xout)
You can see if one of the states is changing over a wide range compared to the others.
There are a couple of things you can do to try to correct this situation. If possible, you may want to rescale the model so that the states are within a couple of orders of magnitude of one another.
Also, you can set specific error tolerances for the integrator blocks in your system. For more information, please refer to 'Specifying the Absolute Tolerance for the Block's Outputs' section in the Integrator block documentation by entering
doc integrator
at the MATLAB command prompt.
  13 Comments
松洁 王
松洁 王 on 14 Apr 2022
Hi Mathworks
I tried check 'States' to log the states as output and run the command plot(tout,xout) after I run the simulation, but there is no xout and tout pamameters. Could you please give some help?
Thanks
Regards
Jack

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More Answers (3)

Sorelys Sandoval
Sorelys Sandoval on 21 Aug 2016
Hi, I had the same problem and the next thing worked for me:
Go to model configuration parameters/Solver/Solver Options: Type: Variable-step Solver: ode15s (stiff/NDF)
and that's all. Hope it works for you :D
  3 Comments

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Shubhangi Bhadoria
Shubhangi Bhadoria on 9 Sep 2016
Hi !
I am stuck in algebric loop which I tried to remove by memory block, algebric constraint block and unit delay but none of them could solve the problem. But If I apply delay of 100 samples, then error is removed but output(performance) is changed completely.
So, I checked if 'one of the states is changing over a wide range compared to the others'. Yes, this is the problem in my model. But I can not resize the model and there os no integrator used. Any suggestions in this regard? How can I fix it? Thanks in advance.

Vivej Sharma
Vivej Sharma on 24 Jan 2018
I am facing this issue.Kindly help.
Algebraic state in algebraic loop containing 'pvboostconvereterIM/PV Array 3/I Filter/First-Order Filter/Model/Sum1' computed at time 1.8060708922720616E-7 is Inf or NaN. 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)
  8 Comments
Monisha R
Monisha R on 30 Jul 2022
An error occurred while running the simulation and the simulation was terminated
Caused by:
Algebraic state in algebraic loop containing 'untitled1/PV Array/Diode Rsh/Product5' computed at time 0.0 is Inf or NaN. 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)
answers please

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