Returns a value which corresponds to the sign of the argument.
SGN         (argument)
             └──┬───┘ 
       Numeric expression
*The parenthesis enclosing the argument can be omitted when the argument is a numeric value of variable.
SGN(A)
argument: Numeric expression
Returns a value of -1 when the argument is negative, 0 when the argument equals 0, and 1 when the argument is positive.
| Argument(X) | SGN(X) | 
|---|---|
| X < 0 | -1 | 
| X = 0 | 0 | 
| X > 0 | 1 | 
10  INPUT "INPUT NUMBERS"; N
20  S = SGN N
30  IF S<>0 THEN PRINT "NOT ZERO": END
40  PRINT "ZERO": END
Uses SGN function to determine whether or not an input value equals 0.