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Plot magnitude and phase of complex derived values

Posted 1 nov 2011, 18:06 GMT-4 2 Replies

phys314
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I have done a frequency response analysis and made a table with frequencies in the first column and integrated strain energies of the second. Each strain energy is complex, which I assume means its magnitude is its maximum value over one cycle, and its phase is the delay of the max relative to the drive. (Tell me if that's wrong)

How do I make a 1D plot of the magnitude (or phase) of this complex data, vs frequency?
2 Replies Last Post 2 nov 2011, 17:07 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2 nov 2011, 02:23 GMT-4
Hi

indeed the phase is the delay w.r.t. the original excitation frequency, normally you have the norm that can be used. In 4.2a you can also split complex values into two real parts (sin-cos, I presume havent had time to study this in detail yet see the "Solver - - Compile Equations" node).

If you resuse complex values for the solving process, take care when you use absolute values of complex items, the realdot() operator is often more adequate, as it allows COMSOL to extract a useful Jacobian, there too check the doc

--
Good luck
Ivar
Hi indeed the phase is the delay w.r.t. the original excitation frequency, normally you have the norm that can be used. In 4.2a you can also split complex values into two real parts (sin-cos, I presume havent had time to study this in detail yet see the "Solver - - Compile Equations" node). If you resuse complex values for the solving process, take care when you use absolute values of complex items, the realdot() operator is often more adequate, as it allows COMSOL to extract a useful Jacobian, there too check the doc -- Good luck Ivar
phys314
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Posted: 1 decade ago 2 nov 2011, 17:07 GMT-4

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