proc iml；
use dif_dif;read all var {col24} into matrix_temp where (col23>15);
use dif_dif;read all var {col24} into matrix_temp2 where (col23< -15);
quit;

col23>15 没有问题，但是col<-15 就无法识别负号

报一下错误：

48 ! read all var {col24} into matrix_temp2 where (col23< -15);
-
22
76
ERROR 22-322: 语法错误，期望下列之一: (, {.