割线法求解非线性方程

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//用割线法求解非线性方程
#include <iostream>
#include <math.h>
#include <process.h>

using namespace std;

class secant
{
private:
int iteration;
double eps, error, f, x_new, x_old1, x_old2;

public:
secant()
{
  iteration = 0;
}
void solution();
double function(double x)
{
  f = 1.55 * pow(x, -0.5) - 7.2 * x + 8.1 * x * x - 4 * pow(x, 3) - 1.3;
  return f;
}
};

void main()
{
secant nonlinear;
nonlinear.solution();
}

void secant::solution()
{
cout << "\n输入初始估值x0和x1：";
cin >> x_old1 >> x_old2;
cout << "\n输入公差";
cin >> eps;
if (fabs(function(x_old1)) < eps)
{
  cout << "\n解是：" << x_old1 << endl;
  exit(0);
}
if (fabs(function(x_old2)) < eps)
{
  cout << "\n解是：" << x_old2 << endl;
  exit(0);
}
do
{
  iteration++;
  if (x_old1 == x_old2)
  {
   cout << "\n遇到了错误x(i) = x(i-1)，异常中断..." << endl;
   exit(0);
  }
  x_new = x_old2 - (function(x_old2) * (x_old2 - x_old1)) / (function(x_old2) - function(x_old1));
  error = fabs(function(x_new));
  x_old1 = x_old2;
  x_old2 = x_new;
}while (error >= eps);
cout << "\n解是：" << x_new << endl;
cout << "\n收敛于" << iteration << "次迭代" << endl;
}