error in computing log values

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F SHEFIN
F SHEFIN on 2 Dec 2021
Commented: F SHEFIN on 6 Dec 2021
Hi sir..My simulink model runs Good for certain values of input...but for some values it gives a complex computation error.I have used a algebraic constraint solver.
An error occurred while running the simulation and the simulation was terminated
Caused by:
  • Domain error. To compute complex results from real x, use 'log(complex(x))'.
  • Error in log.m (line 14) coder.internal.error('Coder:toolbox:ElFunDomainError',mfilename); Error in 'ExitMoles/OutletEnthalpy' (line 20)
  11 Comments
F SHEFIN
F SHEFIN on 2 Dec 2021
Sir...i have attached the model..
there are 4 inputs..actualyy...T,Ratio,Fuel,Per the output is next to the solver...
pls keep T as 100 at every trail.
For all values of Ratio @ 1 per i am getting my answer..
When ratio changes to 1 simulink doesnt compute @ 0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9 ...but computes @ 1 per
when ratio changes ti 2 , simulink doesnt compute @ 0.3 to 0.9....but computes @ 0.1, 0.2,1 per.
similarly for ratio 3 and 4 some values are alone getting computed,
But when ratio is 5 i am able to compute @ all the per values.
It is not simulating for some values...i hope i was clear withe the problem. Thank you

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Answers (1)

Mathieu NOE
Mathieu NOE on 2 Dec 2021
hello
the "log" error was just a consequence of an algebraic loop of OutletEnthalpy bloc : (its input is dependant of the P output)
so probably log of zero or NaN or negative Tad would trigger the error.
simply added a memory block on the P input signal of the OutletEnthalpy bloc and seems the simulation runs fine now (as far I can tell)
  13 Comments
F SHEFIN
F SHEFIN on 6 Dec 2021
Thank you sir....Merry Christmas

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