Definition
An Analytic (Complex Analysis) function has a singularity if it is not analytic at that point . (undefined, discontinuity, non-differentiable, …)
Examples
- is not differentiable at .
- is undefined at .
- is not continuous at any .
Classification of Singularities
- Removable Singularity
- Isolated Singularity/Pole
- Essential Singularity
- Non-isolated Singularity