geo/definite_integral.hpp

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• Last update: 2023-09-03 02:59:23+09:00
• Include: #include "geo/definite_integral.hpp"

Verified with

• test/yukicoder/1319.test.cpp

Code

template <typename Re, typename F>
Re definite_integral(Re a, Re b, F f, int n) {
  Re I = 0;
  Re dx = (b - a) / n;
  Re fl = 0, fr = f(a);
  FOR(i, n) {
    Re lx = a + dx * i;
    Re rx = lx + dx;
    fl = fr;
    fr = f(rx);
    Re fm = f((lx + rx) / 2);
    I += fl + 4 * fm + fr;
  }
  return I * dx / 6;
}

#line 1 "geo/definite_integral.hpp"
template <typename Re, typename F>
Re definite_integral(Re a, Re b, F f, int n) {
  Re I = 0;
  Re dx = (b - a) / n;
  Re fl = 0, fr = f(a);
  FOR(i, n) {
    Re lx = a + dx * i;
    Re rx = lx + dx;
    fl = fr;
    fr = f(rx);
    Re fm = f((lx + rx) / 2);
    I += fl + 4 * fm + fr;
  }
  return I * dx / 6;
}

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