Understanding Branch Points for (1-z^3)^{1/2}

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(1-z^3)^{1/2} has three branch points at z=1, z=\omegaand z=\omega^2 where \omega = e^{2\pi i/3}

The branch points are the zeros of the function correct?

So why are not z=\omega^4, z=\omega^6, z=\omega^8 etc also branch points as they are zeros of the function?
as
(e^{2\pi i/3^3})^6 =e^{2\pi i^6} = e^{12\pi i} = 1 so all even numbered powers of \omega are zeros of the function

also why does the latex code move around vertically like this?
 
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Hi BWV! :smile:

(\omega^{n})^3 = 1 for any n:

(\omega^{n})^3 = (e^{\frac{2n\pi}{3}})^3 = e^{2n\pi} = (e^{2\pi})^n = 1 :smile:

also why does the latex code move around vertically like this?

If you mean why doesn't it stay on the same line as ordinary text, the answer is:

:biggrin: 'cos it doesn't! :biggrin:

But you can make it stay on the line by using [noparse]and instead of and[/noparse] ("itex" stands for "inline tex") … but that has the disadvantage that it squeezes it vertically into the line, so fractions and powers get squashed. :mad:

Alternatively, you can type the whole thing in latex, enclosing each bit of ordinary text inside the brackets of "\text{}":smile:
 
BWV said:
(1-z^3)^{1/2} has three branch points at z=1, z=\omegaand z=\omega^2 where \omega = e^{2\pi i/3}

The branch points are the zeros of the function correct?

So why are not z=\omega^4, z=\omega^6, z=\omega^8 etc also branch points as they are zeros of the function?
as
(e^{2\pi i/3^3})^6 =e^{2\pi i^6} = e^{12\pi i} = 1 so all even numbered powers of \omega are zeros of the function

also why does the latex code move around vertically like this?
\omega= e^{2\pi /3} is the "principal cube root" of 1. That is, \omega^3= 1. We don't talk about \omega^4 because \omega^4= (\omega^3)(\omega)= (1)(\omega)= \omega. Similarly, \omega^6= (\omega)^3(\omega^3)= (1)(1)= 1 and \omega^8= (\omega)^3(\omega^3)(\omega^2)= (1)(1)(\omega^2)= \omega^2.
 
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