Contents
factorial()
A function returning the factorial of the supplied integer
factorial() is a system function returning the factorial of the supplied integer.
factorial() was added in PostgreSQL 7.0.
Usage
factorial ( bigint ) → numeric
Change history
- PostgreSQL 14
- factorial of negative numbers disallowed (commit 0a40563e)
- PostgreSQL 8.0
- PostgreSQL 7.0
- added (commit 64568100)
Examples
Usage example for factorial():
postgres=# SELECT x, factorial(x) FROM generate_series(0,10) AS x; x | factorial ----+----------- 0 | 1 1 | 1 2 | 2 3 | 6 4 | 24 5 | 120 6 | 720 7 | 5040 8 | 40320 9 | 362880 10 | 3628800 (11 rows)
Attempting to obtain the factorial of a negative number (PostgreSQL 14 and later):
postgres=# SELECT factorial(-1); ERROR: factorial of a negative number is undefined
Note that in PostgreSQL 13 and earlier, the function will erroneously return 1:
postgres=# SELECT factorial(-1);
factorial
-----------
1
(1 row)
References
- PostgreSQL documentation: Mathematical Functions