FACTDOUBLE Function (LibreOffice Calc)
The FACTDOUBLE function in LibreOffice Calc returns the double factorial of a non‑negative integer. It is essential in combinatorics, probability, special functions, and advanced mathematical modeling.
Compatibility
▾| Excel | ✔ |
| Gnumeric | ✔ |
| Google_sheets | ✔ |
| Libreoffice | ✔ |
| Numbers | ✔ |
| Onlyoffice | ✔ |
| Openoffice | ✔ |
| Wps | ✔ |
| Zoho | ✔ |
What the FACTDOUBLE Function Does ▾
- Computes the double factorial of a non‑negative integer
- Defined as:
n!! = n × (n‑2) × (n‑4) × … - Even and odd numbers follow different sequences
- Used in combinatorics, probability, and special functions
It is designed to be precise, efficient, and universally compatible.
Syntax ▾
FACTDOUBLE(number)
Arguments
- number:
A non‑negative integer.
Non‑integer values are truncated.
Basic Examples ▾
Double factorial of an even number
=FACTDOUBLE(8)
Computes: 8 × 6 × 4 × 2 = 384.
Double factorial of an odd number
=FACTDOUBLE(7)
Computes: 7 × 5 × 3 × 1 = 105.
Double factorial of zero or negative one
=FACTDOUBLE(0)
Returns 1.
=FACTDOUBLE(-1)
Returns 1.
FACTDOUBLE with non‑integer input
=FACTDOUBLE(7.9)
Equivalent to FACTDOUBLE(7) → returns 105.
Advanced Examples ▾
Relationship to standard factorial (even n)
=FACT(A1) / (2^(A1/2) * FACT(A1/2))
Equivalent to FACTDOUBLE(A1) when A1 is even.
Relationship to standard factorial (odd n)
=FACT(A1) / (2^((A1-1)/2) * FACT((A1-1)/2))
Equivalent to FACTDOUBLE(A1) when A1 is odd.
Double factorial for permutations of perfect matchings
=FACTDOUBLE(A1 - 1)
Used in combinatorics of pairings.
Double factorial in probability distributions
=FACTDOUBLE(2*A1 - 1)
Appears in normal distribution integrals and special functions.
Double factorial for geometric formulas
=FACTDOUBLE(2*A1 - 1) / (2^A1)
Used in spherical volume and surface area formulas.
Manual double factorial using PRODUCT
=PRODUCT(A1; A1-2; A1-4; ...)
Equivalent to FACTDOUBLE(A1).
Double factorial for binomial expansions
=FACTDOUBLE(2*A1 - 1) / FACTDOUBLE(2*A1)
Used in advanced combinatorial identities.
Common Errors and Fixes ▾
Err:502 — Invalid argument
Occurs when:
- number is negative (other than -1)
- number is text
- number cannot be coerced to a non‑negative integer
Err:503 — Overflow
Occurs when:
- number is too large
- double factorial exceeds Calc’s numeric limit
FACTDOUBLE returns unexpected results
Cause:
- Non‑integer values are truncated
Example:FACTDOUBLE(6.8)→FACTDOUBLE(6)→48.
Best Practices ▾
- Use FACTDOUBLE for combinatorics and special functions
- Avoid large inputs (double factorials grow rapidly)
- Use FACT for standard factorials
- Use COMBIN and PERMUT for structured combinatorics
- Use PRODUCT for manual double factorials
Related Patterns and Alternatives ▾
- Use FACT for standard factorials
- Use COMBIN for combinations
- Use COMBINA for combinations with repetition
- Use PERMUT for permutations
- Use PERMUTATIONA for permutations with repetition
- Use PRODUCT(A1; A1-2; …) for manual double factorials
By mastering FACTDOUBLE and its related combinatorics functions, you can build powerful probability, counting, and number theory models in LibreOffice Calc.