Manuals/calci/FACTDOUBLE

FACTDOUBLE(N)

• where, $N$ is a positive integer whose double factorial is to be found.

FACTDOUBLE() calculates the double factorial of a number.

Description

FACTDOUBLE(N)

e.g. FACTDOUBLE(6) displays 48 as a result.

• $N$ should be a positive integer.
• The factorial of an even number is calculated as -

$N!!=N*(N-2)*(N-4)*.....4*2$

• The factorial of an odd number is calculated as -

$N!!=N*(N-2)*(N-4)*.....3*1$

• If $N$ is negative, Calci displays #N/A error message.
• If $N$ is not an integer, it is truncated to calculate the double factorial.
• If $N$ is invalid, Calci displays #NULL error message.
• The double factorial of series of numbers can be calculated as -

e.g. FACTDOUBLE(1..5) calculates double factorial of numbers from 1 to 5 and displays result as 1 2 3 8 15.

Examples

Function	Output
FACTDOUBLE(7)	105
FACTDOUBLE(0)	1
FACTDOUBLE(4.2)	8
FACTDOUBLE(8)	384

Related Videos

FACTDOUBLE

See Also

• FACT

References

• Double Factorial

• List of Main Z Functions

• Z3 home