If a function is analytic at all its points of a bounded domain except...
Exceptional Points in the Context of Analytic Functions
When discussing analytic functions in complex analysis, there are certain points in a bounded domain where the function may not behave as expected. These points are known as exceptional points, and they can take different forms depending on the specific behavior exhibited at those points.
Zeros
Zeros, also known as roots or roots of unity, are points where the function evaluates to zero. In other words, if we substitute a value into the function and obtain zero as the output, that value is considered a zero of the function. Zeros can be thought of as points where the graph of the function intersects the x-axis.
Singularities
Singularities are points where the function is not defined or becomes infinite. They represent a breakdown in the behavior of the function at that particular point. Singularities can take different forms, including removable singularities, poles, and essential singularities.
Removable Singularities
A removable singularity occurs when a function approaches a finite limit as it approaches a particular point. In other words, the function can be extended or "removable" to include that point by assigning a suitable value. It does not disrupt the analytic behavior of the function in the surrounding region.
Poles
Poles are points where the function becomes infinite or undefined. They are characterized by the function approaching infinity as it approaches the pole. Poles can be classified as simple poles, double poles, triple poles, etc., depending on the order of the pole. A simple pole has an order of 1.
Essential Singularities
Essential singularities are points where the function exhibits neither a finite limit nor approaches infinity. The function oscillates or behaves in a complex manner near these points. Essential singularities are considered the most severe type of singularity.
Simple Points
A simple point is a term used to describe a point where a function is well-behaved and possesses all the properties expected of an analytic function. It is non-singular, meaning it is neither a zero nor a singularity of any kind.
Summary
In summary, when a function is analytic at all its points in a bounded domain except for finitely many points, these exceptional points can be classified as zeros, singularities (including removable singularities, poles, and essential singularities), or simple points. Each of these exceptional points represents different behaviors or characteristics of the function at those specific points.