c - 如何使用级数 sinx = x - (x3/3) 计算三角比! + (x5/5)i - (x7/7)! + 一个 C 程序

Question

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Answer 1

如果问题是如何总结这个系列，你可以一个一个地更新术语:

double sum_the_series(double x, size_t number_of_terms)
{
  const double x2 = x * x;

  double term = x;
  double result = term;

  for (size_t i = 1; i < number_of_terms; ++i)
  {
    term = term * x2 / (double(2*i) * double(2*i+1));
    if (i % 2 == 0) result += t;
    else            result -= t;
  }

  return result;
}