The FACTDOUBLE function in Google Sheets is a specialized mathematical function that computes the double factorial of a non-negative integer. The double factorial of a number, denoted as n!!, is the product of all the integers from 1 to n that have the same parity (even or odd) as n. This function is particularly useful in advanced combinatorial calculations and mathematical modeling.

Syntax

FACTDOUBLE(number)

• number: A non-negative integer for which the double factorial is to be calculated.

Example #1

FACTDOUBLE(5)

This function calculates the double factorial of 5, which equals 5 × 3 × 1 = 15.

Example #2

FACTDOUBLE(6)

Here, the function evaluates the double factorial of 6, resulting in 6 × 4 × 2 = 48.

Example #3

FACTDOUBLE(0)

In this case, the function returns 1 because the double factorial of 0 is defined as 1.

Error handling

• ERROR: Invalid argument: This message appears when the input is not a non-negative integer.
• ERROR: Argument must be a number: This indicates that the input provided is of a different type, such as text or a special character.

Conclusion

In summary, the FACTDOUBLE function serves as a valuable tool for calculating the double factorial of a non-negative integer in Google Sheets. Understanding its syntax and application can greatly enhance your mathematical computations, particularly in contexts involving combinatorial queries and advanced statistical analysis.