chase_after.cpp

数值分析的实验报告

#include<iostream>
using namespace std;
#define N 2
#define MAX 100
void chase_after(double (*A)[N],double *f,double *X)
{
	int i;
	double a[N],b[N],c[N-1],n[N];				//n is up triangle 
	for(i=0;i<N-1;i++)							//unit matrix value
	{											//which is not 1
		a[i+1]=A[i+1][i];
		b[i]=A[i][i];
		c[i]=A[i][i+1];
	}
	b[N-1]=A[N-1][N-1];
	n[0]=c[0]/b[0];								//figure out n
	for(i=1;i<N;i++)
		n[i]=c[i]/(b[i]-a[i]*n[i-1]);
	double Y[N];								//figure out Y from Ly=f
	Y[0]=f[0]/b[0];
	for(i=1;i<N;i++)
		Y[i]=(f[i]-a[i]*Y[i-1])/(b[i]-a[i]*n[i-1]);
	X[N-1]=Y[N-1];								//figure out X from Ux=y
	for(i=N-2;i>=0;i--)
		X[i]=Y[i]-n[i]*X[i+1];
}
int main()
{
	double A[N][N],B[N],X[N];
	double L[N][N],U[N][N];
	int i;
	initialnise(A,B);

	for(i=0;i<N;i++)							//show X
		cout<<cout.width(10)<<X[i];
	cout<<endl;
	chase_after(A,B,X);							//chase_after method
	for(i=0;i<N;i++)							//show X
		cout<<cout.width(10)<<X[i];
	cout<<endl;
	return 0;
}