# what dose z represent in this graph?

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Aisha Mohamed on 26 Aug 2022
Commented: Torsten on 26 Aug 2022
I am studying these graphs , and I really confused in some points here.
1- when we take arbitrary point in this figure for example as we can see in the first figure (x= -0.465, y=0.325, z=0.0084), we see that z>0 (greter than 0)
but when we calculate (cos(angle(-0.465+0.325i))) , we got it = -.8196 <0 (les than zero ))
it is clear from this figure z does not equal the value of the function (cos(angle(-0.465+0.325i))), and
if z indicate to the sign of this function , why we got z>0 whereas the value of this function <o?
My questions are,
Is z in this figure indiacet to the value of (cos(angle(-0.465+0.325i))) or only tells us where (cos(angle(-0.465+0.325i))) positinve and negative? and why we find this contrast?
I will appreciate any help.
Walter Roberson on 26 Aug 2022
My answer was in preparation when you posted yours. We happened to close to the same thing.
Torsten on 26 Aug 2022
Maybe I'm blind, but where do you get from that f_k(z) = z ?