dfbv.cpp

自己写的有关计算矩阵的小程序

#include "iostream.h"
#include "math.h"

void main()
{
	float a[10][10],b[10],d=0,t=0,sum=0;
	int k=1,l=0,i=0,j=0,m,n;
	cout<<"输入方程组组数:"; 
	cin>>n;
	cout<<"输入方程组未知数:"; 
	cin>>m;
	cout<<"输入方程组名项系数:"; 
	for(int ii=1;ii<=n;ii++)
	{
		cout<<"第 "; 
		for(int jj=1;jj<=m;jj++) cin>>a[ii][jj];
		cin>>b[ii];
	}
	while(k<=n)
	{
		//*****选主元素*****
		d=a[k][k];
		l=k;
		for(i=k+1;i<=n;i++)
		{
			if(fabs(a[i][k])>fabs(d))
			{
				d=a[i][k];
				l=i;
			}
		}
		if(l!=k)
		{
			for(j=k;j<=n;j++)
			{
				t=a[l][j];a[l][j]=a[k][j];a[k][j]=t;
			}
			t=b[k];b[k]=b[l];b[l]=t;
		}
		//**************
		//*****消元*****
		for(j=k+1;j<=n;j++)
		{
			a[k][j]=a[k][j]/a[k][k];
		}
		b[k]=b[k]/a[k][k];
		for(i=k+1;i<=n;i++)
		{
			for(j=k+1;j<=n;j++)
			{
				a[i][j]=a[i][j]-a[i][k]*a[k][j];
			}
			j=1;
			b[i]=b[i]-a[i][k]*b[k];
		}
		k++;
		//**************
	}
	//*****回代*****
	for(i=n-1;i>=1;i--)
	{
		sum=0;
		for(j=i+1;j<=n;j++)
		{
			sum=sum+a[i][j]*b[j];
		}
		b[i]=b[i]-sum;
	}
	//**************
	cout<<"最后结果:"; 
	for(int loop=1;loop<=n;loop++)
	{
		cout<<b[loop];
		cout<<endl;

	}
}