When is the Uvarov transformation positive definite?

Matthias Humet, Marc Van Barel. When is the Uvarov transformation positive definite?. Numerical Algorithms, 59(1):51-62, 2012. [doi]

@article{HumetB12,
  title = {When is the Uvarov transformation positive definite?},
  author = {Matthias Humet and Marc Van Barel},
  year = {2012},
  doi = {10.1007/s11075-011-9475-4},
  url = {http://dx.doi.org/10.1007/s11075-011-9475-4},
  researchr = {https://researchr.org/publication/HumetB12},
  cites = {0},
  citedby = {0},
  journal = {Numerical Algorithms},
  volume = {59},
  number = {1},
  pages = {51-62},
}