1.cpp

这是一个列主元消去法的VC程序

#include<iostream.h>
#include<stdlib.h>
#define a(i,j)  a[i*(n+1)+j]
float f(float s)
{ if(s<0) return -s;
   else  return s;
}
void sc(float a[],int n)
{ int k,j;
	for(k=0;k<n;++k)
  {cout<<endl;
  for(j=0;j<n+1;++j)
	  cout<<a(k,j)<<"  ";
  }
  cout<<endl;
}
void main()
{ int i,j,n,k;
  cout<<"请输入您要计算的阶数:";
  cin>>n;
  float *a,s;  
  a=new float[n*(n+1)];
	  cout<<"input A("<<n<<"*"<<n<<")"<<endl;
  for(i=0;i<n;++i)
    for(j=0;j<n;++j)

		cin>>a(i,j);
  cout<<"input b:"<<endl;
  for(j=0;j<n;++j)
  cin>>a(j,n);
  sc(a,n);
  for(i=0;i<n-1;++i)
  {  s=a(i,i);k=i;
     for(j=i+1;j<n;++j)
       if(f(s)<f(a(j,i))) {s=a(j,i);k=j;}
     if(s==0) { cout<<"det(A)=0";exit(1);}
	 if(k!=i)
     for(j=0;j<n+1;++j)
	 { s=a(k,j);
	   a(k,j)=a(i,j);
	   a(i,j)=s;
     }
     for(k=i+1;k<n;++k)
	  for(j=n;j>=i;--j)
	   a(k,j)-=a(i,j)*a(k,i)/a(i,i);
  sc(a,n); 
  }
  i=n-1;j=n;
  a(i,j)/=a(i,i);
  for(i=n-2;i>=0;i--)
  { s=0;
    for(j=i+1;j<n;++j)
    s+=a(i,j)*a(j,n);
    a(i,n)=(a(i,n)-s)/a(i,i);
  }
  cout<<endl;
  for(i=0;i<n;++i)
  cout<<"x"<<i+1<<"="<<a(i,n)<<endl;
  delete a;
}