GeneratorInterface/ExhumeInterface/plugins/Integral.cpp - master - githubmirror/cmssw

GeneratorInterface/ExhumeInterface/plugins/Integral.cpp

21 строка420 B

Matti Kortelainen

Move contents of ExhumeHadronizer.{h,cc} to ExhumeGeneratorFilter

16 мар 2026, 11:45

16 мар 2026, 11:45c901e15

//Simpson integrator, written to mirror CERNLIBS one

#include <cmath>

double dsimps_(double* F, double* A, double* B, int* N) {
  double a = *A;
  double b = *B;
  int n = *N;
  double deltaX = (b - a) / n;
  double I = F[0] + F[n];

  for (int i = 1; i <= n / 2; i++) {
    int j = 2 * i;
    int k = 2 * i - 1;
    if (j < n)
      I += 2 * F[j];
    if (k < n)
      I += 4 * F[k];
  }
  return (I * deltaX / 3);
}