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Simulink embedded function detects phantom complex value

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Victor
Victor 2012-2-10
评论： DURODOLA Taiwo 2019-8-5
I have an embedded function block in my Simulink model containing a natural log function that calculates an output value based on inputs that go in the numerator or denominator of the log. When I run the simulation, an error message pops up saying that I'm trying to take the log of a complex value. I am constantly tracking the values that go inside this function and none of them are approaching zero or a very high number, but I still keep getting an error. What do you think could be the problem?

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回答（3 个）

Umar Farooq
Umar Farooq 2016-12-7
I want to simulate wind generation model in simulink. i connected a bus with the output "m" of the wind generator to collect voltage and current and further connected a scope to see the results. when i try to run the simulation i get this error
Complex signal mismatch. Output port 1 of 'wind/Signal Specification1' is a signal of numeric type complex. However, it is driving a signal of numeric type real
Kindly help me with this.
Walter Roberson
Walter Roberson 2012-2-11
编辑：Walter Roberson 2019-7-31
That message could potentially mean that the inherited signal type for that signal is marked as complex, because it resulted from a sequence of steps that could potentially produce complex values for some arguments and constants (even if it is never possible in with the arguments and constants that you are using.)
Just to throw out an example: arccos "could" produce complex outputs if you happened to feed it values outside of -1 to 1. You might know for other reasons that your inputs were always in that range, but Simulink might not have been able to establish that with the information it had and the proof algorithms it uses.
If this is the problem, that the signal type is marked as complex, then I gather there are two possible solutions: pass the signal through a block that Simulink knows selects only the real part, Or instead of inheriting the signal type, force it to real (preferably back at the output stage of whatever Simulink is thinking could create the complex value.)
(I have never used Simulink myself, but there was a question with this resolution perhaps 7 or 8 months ago and the solution lurked in my memory.)
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zunaira
zunaira 2013-1-31
Can you please share the solution ,as I am encountering with same problem? Thanking you in advance
DURODOLA Taiwo
DURODOLA Taiwo 2019-8-5
Thanks Mr Roberson;
But which block can i can i employ to force the complex output value to a real value.
Thanks, God bless.
You may however, help review the model. It's attached herewith

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DURODOLA Taiwo
DURODOLA Taiwo 2019-7-31
Simulation file
Please find above the attached file. i wil appreciate if solution id proffered

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