data a;
start=1;
end=2;
do until(range(start,end) le 0.0001);
   y1=log(start)+start-1.5;
   temp=(start+end)/2;
   y2=log(temp)+temp-1.5;
   y3=log(end)+end-1.5;
   if y1*y2<0 then do;
   end=temp;
   end;
   else if y1*y3<0 then do;/*有赋值语句时最好使用do组*/
   start=temp;
   end;
   put y1=;
   put y2=;
   put y3=;
   put start=;
   put temp=;
   put end=;
end;
final_value=(start+end)/2;
put start=;
put end=;
put final_value;
run;