Integrating smooth periodic functions (opens in new tab)

Several posts lately have looked at the function f(x) = cos(sin(x) + x). This post will look at the function from a different angle. It’s a smooth function with period 2π, and it’s very flat at odd multiples of π, i.e. the first five derivatives are zero. For reasons I wrote about here, this means that […] The post first appeared on .