mathematics

If the underlying TChain has no name (""), then the output of SaveGraph is far from helpful.
The following script:

#include<ROOT/RDataFrame.hxx>
#include<ROOT/RDFHelpers.hxx>
#include<TSystem.h>

using namespace ROOT;

int main(){
  ROOT::RDataFrame(1).Define("x", "42").Snapshot("t", "f.root");

  TChain ch("");
  ch.Add("f.root?#t");
  RDataFrame df(ch);
  auto df2 = df.Coun

IEEE 754 recommends (but does not require) a compound function, which is in the process of being standardized for C and C++; we should expose it in swift-numerics. The simplest, most literal translation of the operation into Swift would be:

extension RealFunctions {
  /// (1+x)ⁿ
  /// 
  /// Returns NaN if x < -1.
  static func compound(_ x: Self, _ n: Int) -> Self {
    // not

What is the feature or improvement you would like to see?

A function that computes the graph center, and the graph periphery. The graph center is the set of vertices that has minimal eccentricity. The periphery is the set with maximal eccentricity.

Use cases for the feature

This is a standard concept in graph theory.

**Implementatio