# I plot these two functions by Matlab but the phase of the both of them look likes strange and I think the plot of the phase is wrong in both of them

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Aisha Mohamed on 27 May 2022
Commented: Jeffrey Clark on 27 May 2022
I plot these two functions by Matlab but the phase of the both of them look likes strange and I think the plot of the phase is wrong in both of them can you help me to correct these figures
the first function is f(z) = (0.10 + 0.3i) + (0.4243 + 0.0017i)*z + (0.9 − 0.001i)*z^2 and its plot is the phase of this function look likes rwrong because for example at Z_R equales zero Z_I increace sharply and I do not know the correct value of Z_I ?
The second function is
f(z) = (0.10 − 0.3i)*z^(−1) + (0.2121 − 0.0008i)*z^(−2) + (0.9 + 0.001i)*z(−3).
and its figure is Also here the phase of the function looks like wrong because for examble at Z_R equales zero Z_I increace sharply and I do not know the correct value of Z_I ?
I appreciate any help
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Jeffrey Clark on 27 May 2022
Phase discontinuity indicates you probably have to unwrap the phase; see Shift phase angles - MATLAB unwrap (mathworks.com). This is commonly done when looking at the phase following FFT.