d2r10.cpp

双三次样条插值方法

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

void main()
{
    //program d2r10
    //driver for routine splie2
	double x1[11], x2[11], y[11][11], y2[11][11],x1x2;
	int m,n,i,j;
    m = 10;
    n = 10;
    for (i = 1; i<=m; i++)
        x1[i] = 0.2 * i;
    for (i = 1; i<=n; i++)
        x2[i] = 0.2 * i;
    for (i = 1; i<=m; i++)
	{
        for (j = 1; j<=n; j++)
		{
            x1x2 = x1[i] * x2[j];
            y[i][j] = x1x2*x1x2;
        }
    }
    splie2(x1, x2, y, m, n, y2);
	cout<<setprecision(6)<<setiosflags(ios::fixed);
    cout<<endl;
    cout<<"Second derivatives from splie2"<<endl;
    cout<<"Natural spline assumed"<<endl;
	cout<<endl;
    for (i = 1; i<=5; i++)
	{
        for (j = 1; j<=5; j++)
            cout<<setw(12)<<y2[i][j];
        cout<<endl;
    }
    cout<<endl;
    cout<<"Actual second derivatives"<<endl;
	cout<<endl;
    for (i = 1; i<=5; i++)
	{
        for (j = 1; j<=5; j++)
            y2[i][j] = 2.0* (x1[i] *x1[i]);
        for (j = 1; j<=5; j++)
            cout<<setw(12)<<y2[i][j];
        cout<<endl;
    }
}