proc iml;
a={1 -2 3,-5 4 0,2 1 0};
b={1,2,3};
do;
if det(a)=0 then goto negative;
     x=inv(a)*b;   print a b x;
        negative:print "The equation is unresolved";
        end;
     run;
  quit;
这里为什么要用DO来限制啊，我刚开始没用DO ，日志窗口就一直显示出错 ，就是下面这个显示有错误
proc iml;
a={1 -2 3,-5 4 0,2 1 0};
b={1,2,3};
if det(a)=0 then goto negative;
     x=inv(a)*b;   print a b x;
        negative:print "The equation is unresolved"
     run;
  quit;
  日志错误信息是这样的NOTE: IML Ready
2    a={1 -2 3,-5 4 0,2 1 0};
3    b={1,2,3};
4    if det(a)=0 then goto negative;
5         x=inv(a)*b;
ERROR: Unresolved label: NEGATIVE
5  !                    print a b x;
ERROR: Matrix x has not been set to a value.

statement : PRINT at line 5 column 20
6        negative:
6  !              print "The equation is unresolved"
7         run;
ERROR: Matrix run has not been set to a value.