Nick

> I removed partial_denominators, because IMO the name is misleading - front element represents integer part, and is not denominator. It may confuse the user that the function returns sth....

> I only found sources where either "Mathworld's definition" is used, or the coefficients b_i have no specific name. So in the end, I suppose that the current form can...

Friends, if you don't mind, I'm going to clean up this thread since it kinda got off topic and many of the off-topic issues have been resolved.

@octopus-prime : Yup. Also that reminds me: Jenkins-Traub.

I think every interpolator has the first derivative implemented. Second derivatives of the quintic B-spline are implemented. Other interpolators have the wrong spectral properties and perform poorly on second derivatives....

@cosurgi : Totally agree it would be useful, but I really like FFTW and it satisfies all my needs, so other things are a higher priority. I don't know who...

@mborland : Should this be merged?

@yurivict : `-fsanitize=thread`?

This seems like a reasonable ask, and not too difficult. Lemme think about how to communicate it.

@jzmaddock : Yup, you're right. Will try to get to this next week.