function flag=APIT(xA,yA,xB,yB,xC,yC,xM,yM)
   %xA=str2num(xxA);xB=str2num(xxB);xC=str2num(xxC);xM=str2num(xxM);command
   %yA=str2num(yyA);yB=str2num(yyB);yC=str2num(yyC);yM=str2num(yyM);command
   xxx1=[xA xB xC];
   yyy1=[yA yB yC];
   [xxx,index]=sort(xxx1);    %对X坐标进行排序
   yyy=[yyy1(index(1)) yyy1(index(2)) yyy1(index(3))];    %对Y坐标进行做相应变换
   max_xxx=xxx(3);
   min_xxx=xxx(1);
   max_yyy=max(yyy);
   min_yyy=min(yyy);
   if ((yM<min_yyy)|(yM>max_yyy))
       flag=0;
   else
       
   if((xB-xA)==0)                  
   xAB=xA;
    elseif((yB-yA)==0)
     xAB=-10;
   else
        xAB=xA+((yM-yA)/(yB-yA))*(xB-xA);  
   end
   if((xC-xB)==0)
   xBC=xC;
   elseif((yC-yB)==0)
     xBC=-10;
   else
        xBC=xB+((yM-yB)/(yC-yB))*(xC-xB); 
   end
   if((xC-xA)==0)
   xAC=xC;
   elseif((yC-yA)==0)
     xAC=-10;
   else
        xAC=xA+((yM-yA)/(yC-yA))*(xC-xA);  
   end
    
   if((xAB<xxx(1))|(xAB>xxx(2)))
       xAB=-10;
   end
    if((xBC<xxx(2))|(xBC>xxx(3)))
       xBC=-10;
    end
    if((xAC<xxx(1))|(xAC>xxx(3)))
       xAC=-10;
    end
   select1=[xAB xBC xAC];
   find_index=find(select1>=0);
   oo=size(find_index,2);
   if(oo<2)
       flag=0;
   else
   for i=1:oo
       select2(i)=select1(find_index(i));
   end
      select2;  %显示选择后的坐标值
    if((xM-select2(1))*(xM-select2(2))<=0)
                flag=1;
    else
        flag=0;
    end
   
   end
   end