Not at all. He is correct that those functions are defined mathematically and that the results should therefore be the same using any libraries which claim to i

Not at all. He is correct that those functions are defined mathematically and that the results should therefore be the same using any libraries which claim to implement them. An example used in the article: https://en.wikipedia.org/wiki/Lanczos_resampling https://en.wikipedia.org/wiki/Lanczos_resampling