data tmp ;
        x = -13 ;
        y = x ** (1/3) ;
        put x= y= ;
run ;


出现如下提示:

522  data tmp ;
523      x = -13 ;
524      y = x ** (1/3) ;
525      put x= y= ;
526  run ;

NOTE: Invalid argument(s) to the exponential operator "**" at line 524 column 11.
x=-13 y=.
x=-13 y=. _ERROR_=1 _N_=1
NOTE: Mathematical operations could not be performed at the following places. The results of
      the operations have been set to missing values.
      Each place is given by: (Number of times) at (Line):(Column).
      1 at 524:11


乘方符号的使用有问题 .  y = x**(1/n) 中, 只要x为负数, 即使n为自然数奇数也报错.    y = x**n 中, x为负数却没任何问题 .