d8r2.cpp

来自「工程算法 这是一个很有用的工程数值算法集锦」· C++ 代码 · 共 48 行

# include<math.h>
# include<iomanip.h>
# include<iostream.h>
# include<stdlib.h>

void main()
{
    //program d8r2
    //driver for routine eigsrt
    int i,nrot,j,np = 3;
    double d[4], v[4][4], a[4][4];
    a[1][1] = 1.0; a[1][2] = 2.0; a[1][3] = 3.0;
    a[2][1] = 2.0; a[2][2] = 2.0; a[2][3] = 3.0;
    a[3][1] = 3.0; a[3][2] = 3.0; a[3][3] = 3.0;
    jacobi(a, np, d, v, nrot);
    cout<< "Unsorted eigenvectors:"<<endl;
    for (i = 1; i<=np; i++)
	{
        cout<< setw(5)<<endl;
        cout<< setw(5)<<"Eigenvalue "<< i<<" = ";
        cout<< d[i];
        cout<<endl;
        cout<< setw(5)<< "Eigenvector:  "<<endl;
        for (j = 1; j<=np; j++)
		{
            cout<<setw(15)<<v[j][ i];
        }
		cout<<endl;
    }
    cout<< endl;
    cout<< setw(5)<< "********** sorting **********"<<endl;
    eigsrt(d, v, np);
	cout<<endl;
    cout<< setw(5)<< "Sorted eigenvectors:"<<endl;
    for (i = 1; i<=np; i++)
	{
        cout<< endl;
        cout<< setw(5)<<"Eigenvalue"<< i<< " = ";
        cout<< d[i]<<endl;
        cout<< setw(5)<< "Eigenvector:"<<endl;
        for (j = 1; j<=np; j++)
		{
            cout<< setw(15)<<v[j][ i];
        }
         cout<< endl;
    }
}