雅可比迭代法.cpp

来自「包含二分法、复化辛卜生公式、改进欧拉法、拉格朗日插值多项式、龙贝格算法、牛顿迭代」· C++ 代码 · 共 57 行

#include<iostream.h>
#include<math.h>
#define EPS 1e-6
#define MAX 100

float *Jacobi(float a[3][4],int n)
{
	float *x,*y,epsilon,s;
	int	  i,j,k=0;

	x =new float[(n*sizeof(float))];	//here must be modifed
	y =new float[(n*sizeof(float))];	//here must be modifed
	for( i=0;i<n;i++ )
		x[i]=0;
	while(1)
	{
		epsilon=0;
		k++;
		for( i=0;i<n;i++ )
		{
			s=0;
			for( j=0;j<n;j++ )
			{
				if(j==i)
					continue;
				s+=a[i][j]*x[j];			
			}		
			y[i] =(a[i][n]-s)/a[i][i];		
			epsilon +=fabs(y[i]-x[i]);
		}
		if(epsilon<EPS)
		{
			cout<<"迭代次数为："<<k<<endl;
			return y;
		}
		if( k>=MAX )
		{
			cout<<"The method is disconvergent";
			return y;
		}
		for( i=0;i<n;i++ )
			x[i]=y[i];		
	}
	return y;
}

void main()
{
	int i;
	float a[3][4]={5.0,2.0,1.0,8.0,2.0,8.0,-3.0,21.0,1.0,-3.0,-6.0,1.0};	//here must be modifed
	float *x;
	x=new float[(3*sizeof(float))];		//here must be modifed
	x=Jacobi(a,3);
	for( i=0;i<3;i++ )
		cout<<"x["<<i<<"]="<<x[i]<<endl;
}