Node analysis

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@-MFra- wrote:

Hi!

Why, in figure 29 of the attached worksheet, do the phases not coincide?

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Because its wrong to just use "atan (Im(z)/Re(z))" to get the phase for any complex number z. To get the correct result you'll have to add or subtract pi if Re(z)<0!

Adding pi gives you the phase in the range ]-pi/2; 3 pi /2] and looks like this:

Subtracting pi forces the phase to ]-3 pi /2; pi/2)

You may use "atan2" instead of "atan" in your function phi to get the very same results as you get with "arg", that is a phase in }-pi; pi]

Using atan2 also has the advantage that the case of Re(z)=0 is handled correctly and does not throw an error!

Of course "arg" would do the job equally well 😉

BTW, to avoid jump discontinuities in the phase plot you can use the "phasecor( )" function  but you have to turn the continuos function into vectors for plotting.