diedai.cpp

迭代发解方程算法

#include<iostream.h>
#include<stdlib.h>
#define p(i,x)  p[(i)*(n+1)+x]
char suoming()
{  cout<<"if use Jacobi diedai,please input j:\n";
   cout<<"if use Gauss-Seidel diedai,please input g:\n";
   cout<<"if use SOR diedai,please input s:\n";
   cout<<"input a char:";
   char c;
   cin>>c;
   return c;
}
void huhuan(float *p1,float *p2,int n)
{ int i;
  float s;
  for(i=0;i<n;++i)
  { s=p1[i];p1[i]=p2[i];p2[i]=s;
  }
} 
void jdiedai(float *p,float *p1,float *p2,int n)
{  int i,j;
   float s;
   for(i=0;i<n;++i)
   {  s=0;
	   for(j=0;j<n;++j)
	   { if(j==i) continue;
	     s+=p(i,j)*p2[j];
	   }
	   p1[i]=(p(i,n)-s)/p(i,i);
   }
}
void sordiedai(float *p,float *p1,float *p2,int n,float w)
{  int i,j;
   float s;
   for(i=0;i<n;++i)
   { s=0;
	   if(i>0)
		   for(j=0;j<i;++j)
			   s+=p(i,j)*p1[j];
		for(j=i;j<n;++j)
		 s+=p(i,j)*p2[j];
		p1[i]=p2[i]+w*(p(i,n)-s)/p(i,i);

   }
}
float f(float s,float t)
{ if(s-t<0)  return t-s;
   else  return s-t; 
}
float wuqiongfan(float *p1,float *p2,int n)
{  int i,j;
	float s=0,t=0;
  for(i=0;i<n;++i)
  { if(i==0)
       for(j=0;j<n;++j)
		   s+=f(p1[j],p2[j]);
	   for(j=1;j<n;++j)
         t+=f(p1[j],p2[j]);
	   if(s<t) s=t;
	   t=0;
  }
  return s;
}
void main()
{ int i,x,n;
  float *p,*p1,*p2,w,epc,s=10,k=0;
  char c;
  cout<<"input the number of equations:";
  cin>>n;
  p=new float[n*(n+1)];
  p1=new float[n];
  p2=new float[n];
  cout<<"input A["<<n<<"*"<<n<<"]:\n";
  for(i=0;i<n;++i)
	  for(x=0;x<n;++x)
		  cin>>p(i,x);
   cout<<"intput b[b1 .... b"<<n<<"]\n";
   for(i=0;i<n;++i)
	   cin>>p(i,n);
   for(i=0;i<n;++i)
	   p2[i]=0;
   c=suoming();
   cout<<"input kong zhi tiao jian:||X(k+1)-X(k)||<?";
   cin>>epc;
   if(c=='s')  {cout<<"please input w:"; cin>>w;}
   if(c=='g') w=1;
   if(c!='j')
     while(s>=epc)
   {  k++;
      sordiedai(p,p1,p2,n,w);
      s=wuqiongfan(p1,p2,n);
	  if(s>=epc) huhuan(p1,p2,n);
   }
   if(c=='j')
    while(s>=epc)
	{  k++;
        jdiedai(p,p1,p2,n);
		s=wuqiongfan(p1,p2,n);
	   if(s>=epc) huhuan(p1,p2,n);
	}
   cout<<"No."<<k<<":"<<endl;
    cout.precision(8);
   cout.setf(ios::fixed);
   for(i=0;i<n;++i)
	   cout<<p1[i]<<endl;
	delete p;
	delete p1;
	delete p2;
}