ASIN

Return the inverse sine value of an input radian value.

ASIN(number)

The return type is a DOUBLE PRECISION number.

For example:
premdb=# select asin(1) from sys.const;
      asin       
-----------------
 1.5707963267949
(1 row)
premdb=# select asin(avg_att/100) from team order by teamid limit 2;
       asin        
-------------------
  0.64280129238978
 0.343622473068933
(2 rows)