Desmos Factorial function I was playing around with gamma function approximations and I was curious of which approximation Desmos uses. It extends negatives so it can’t be the Stirling formula. Does anyone know what it is?

Ok so I think I found what it uses. Thanks to @eyeballfrog for suggesting the reflection formula. I did a bit of research and found the Lanczos Approximation combined with the reflection formula to match the factorial function is Desmos almost perfectly. Here is the graph. I’ve also made a C++ implementation of the algorithm if anyone else wants to use it here
