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Meromorphic Functions

Functions that are holomorphic on an open subset of the complex plane except for a set of isolated points.

Sequence of Expressions

Property

Properties

Since poles are isolated, there are at most countably many for a meromorphic function. The set of poles can be infinite, as exemplified by the function f(z)=cscz=1sinz.f(z)=\csc z={\frac {1}{\sin z}}. By using analytic continuation to eliminate removable singularities, meromorphic functions can be added, subtracted, multiplied, and the quotient f/gf/g can be formed unless g(z)=0g(z)=0 on a connected component of D. Thus, if D is connected, the meromorphic functions form a field, in fact a field extension of the complex numbers. In several complex variables, a meromorphic function is defined to be locally a quotient of two holomorphic functions. For example, f(z1,z2)=z1/z2f(z_{1},z_{2})=z_{1}/z_{2} is a meromorphic function on the two-dimensional complex affine space. Here it is no longer true that every meromorphic function can be regarded as a holomorphic function with values in the Riemann sphere: There is a set of "indeterminacy" of codimension two (in the given example this set consists of the origin (0,0)(0,0) ). Unlike in dimension one, in higher dimensions there do exist compact complex manifolds on which there are no non-constant meromorphic functions, for example, most complex tori. - ^Cite error: The named reference Lang_1999 was invoked but never defined (see the help page).
Intermediate
Every bounded entire function must be constant.\nf(z)M    f(z)=c|f(z)| \le M \implies f(z) = c