求解线性方程组之Thomas法

//Thomas法求解三对角方程组
#include
#include

using namespace std;

class tridiagonal
{
private:
 int i, n;
 double *x, *a, *b, *c, *beta, *gamma, *r;

public:
 void input();
 void tridiagonal_solution();
 ~tridiagonal()
 {
  delete[] x, a, b, c, beta, gamma, r;
 }
};

void main()
{
 tridiagonal tridiag;
 tridiag.input();
 tridiag.tridiagonal_solution();
}

void tridiagonal::input()
{
 cout << "\n输入方程的个数：";
 cin >> n;
 a = new double[n-1];
 b = new double[n];
 c = new double[n-1];
 beta = new double[n];
 gamma = new double[n];
 r = new double[n];
 x = new double[n];
 for (i = 0; i < n; i++)
 {
  cout << "\n输入b[" << i << "] = ";
  cin >> b[i];
 }
 for (i = 0; i < (n-1); i++)
 {
  cout << "\n输入c[" << i << "] = ";
  cin >> c[i];
 }
 for (i = 1; i < n; i++)
 {
  cout << "\n输入a[" << i << "] = ";
  cin >> a[i-1];
 }
 for (i = 0; i < n; i++)
 {
  cout << "\n输入r[" << i << "] = ";
  cin >> r[i];
 }
}

void tridiagonal::tridiagonal_solution()
{
 for (i = 0; i < n; i++)
 {
  if (i == 0)
  {
   beta[0] = b[0];
   gamma[0] = r[0] / beta[0];
  }
  else
  {
   beta[i] = b[i] - a[i-1]*c[i-1]/beta[i-1];
   gamma[i] = (r[i] - a[i-1]*gamma[i-1])/beta[i];
  }
 }
 x[n-1] = gamma[n-1];
 for (i = (n-2); i >= 0; i--)
 {
  x[i] = gamma[i] - c[i]*x[i+1]/beta[i];
 }
 for (i = 0; i < n; i++)
 {
  cout << "\nx[" << i << "] = " << x[i] << endl;
 }
}