- #1

binbagsss

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**So a mobius transformation is defined as [itex]\frac{az+b}{cz+d}[/itex]=f(z).**

*Where ad-bc≠0.***My question is just deriving this condition ad-bc≠0.**

I understand that the condition describes the case were the mapping leaves

**all**points unchanged. This is

**described**as undefined in some textbooks...(why is this, isn't it then just an identity map?)

But not by setting z=f(z).

I can't see why this condition would not equally be desribed by z=f(z)?

Many Thanks for any assistance.

Many Thanks for any assistance.