被逼近函数和lagrange插值函数.txt

数值分析的一下算法 及源代码 exe 压缩文件

int i,j,e;
   float x,y,p_x,p_y,temp,xx[11],yy[11],mm[11],sum,p_sum;
   Form1->Canvas->Pen->Color=clBlack;//轴色
   Form1->Canvas->MoveTo(100,300);Form1->Canvas->LineTo(450,300);//横轴
   Form1->Canvas->MoveTo(300,50);Form1->Canvas->LineTo(300,400);//纵轴
   Form1->Canvas->TextOut(x+150,-y+304,"-1");
   Form1->Canvas->TextOut(x+290,-y+304,"0");
   Form1->Canvas->TextOut(x+440,-y+304,"1");
   Form1->Canvas->Pen->Color=clBlue;//线色
   Form1->Canvas->MoveTo(x+20,-y+255);Form1->Canvas->LineTo(x+50,-y+255);//横线
   Form1->Canvas->TextOut(x+50,-y+250,"被逼近函数");//文字叙述
   Form1->Canvas->Pen->Color=clRed;//线色
   Form1->Canvas->MoveTo(x+20,-y+210);Form1->Canvas->LineTo(x+50,-y+210);
   Form1->Canvas->TextOut(x+50,-y+200,"Lagrange插值");

   Form1->Canvas->Pen->Color=clBlue;//曲线颜色
   x=-1.0,y=1/(1+25*x*x);
   p_x=x*150+300,p_y=-y*150+300;
   Form1->Canvas->MoveTo(p_x,p_y);
   for (x=-1.0;x<=1.0;)
   {
       y=1/(1+25*x*x);
       p_x=x*150+300,p_y=-y*150+300;
       Form1->Canvas->LineTo(p_x,p_y);
       x+=0.0001;
   }


   Form1->Canvas->Pen->Color=clRed;
   x=-1.0;
   for(i=0;i<=10;i++)
   {
       yy[i]=1/(1+25*x*x);
       xx[i]=x;
       x+=0.2;
   }
   x=-1.0,y=1/(1+25*x*x);
   p_x=x*150+300,p_y=-y*150+300;
   Form1->Canvas->MoveTo(p_x,p_y);
   for(e=0;e<=1000;e++)
   {
      sum=0;
      for(i=0;i<=10;i++)
      {
          temp=1;
          for(j=0;j<=10;j++)
          {
             if(i!=j)
               temp=temp*(x-xx[j])/(xx[i]-xx[j]);
          }
          sum+=yy[i]*temp;
      }
      p_x=x*150+300,p_y=-sum*150+300;
      Form1->Canvas->LineTo(p_x,p_y);
      x+=0.002;
   }

}