How to return "NaN" using SQRT function in Oracle SQL?

Question

How to return "NaN" using SQRT function in Oracle SQL? Here is my unsuccessful attempt:

SELECT SQRT(4) AS "SQRT of 4",
 SQRT(0) AS "SQRT of 0",
 SQRT(-1) AS "SQRT of -1"
FROM DUAL;

As I understand, a successful query might use the TO_BINARY_DOUBLE function but additional approaches are welcome.

Answer 1

Cast the number, as you said:

SELECT SQRT(4) AS "SQRT of 4",
 SQRT(0) AS "SQRT of 0",
 SQRT(TO_BINARY_DOUBLE(-1)) AS "SQRT of -1"
FROM DUAL;