Get Your Numbers Right
Returns the double factorial of a number, with up to 32,767 significant digits of precision. Same as Excel's built-in FACTDOUBLE function, but with high precision.
The double factorial of a number is the product of every other positive integer equal to or less than the source number.
|num||Required. The number for which the double factorial will be returned.|
|format_negative||Optional. Determines whether
negatives are formatted with a leading hyphen ("-"), or parentheses ("()").
Set to 1 to format negatives with a leading hyphen. Set to 2 for
parentheses. 1 by default.
You can also format negatives with a red font.
|format_thousands||Optional. Determines whether thousands separators are included. Set to TRUE to include thousands separators. FALSE by default.|
|format_currency||Optional. Determines whether currency symbol is included. Set to TRUE to include currency symbol. The currency symbol will be added either to the beginning or to the end of the result, whichever is appropriate for the locale. FALSE by default.|
|exponential_notation||Optional. Determines whether result is formatted in exponential notation. Set to TRUE to format in exponential notation. FALSE by default.|
|maximum_significant_digits||Optional. Determines the maximum number of significant digits to be returned. Default is 100, or the user's custom maximum set in the About box, or the maximum number allowed by the edition of xlPrecision, whichever is less.|
If num is negative, an error will be returned.
If num is 0, 1 is returned. The double factorial of 0 is defined as 1.
xlpFACTDOUBLE cannot return a factorial for a number larger than 17,234. If num is over 17,234, an error will be returned.
xlPrecision results are returned as text that look like numbers, not as values that Excel recognizes as numbers. This is because Excel would truncate the results to 15 significant digits if it recognized them as numbers.
format_negative, format_thousands, format_currency, and exponential_notation are all ignored by the 25 SD edition of xlPrecision.
format_thousands and exponential_notation are ignored by the 35 SD edition of xlPrecision.
maximum_significant_digits is ignored if it is higher than the maximum significant digits allowed by the edition of xlPrecision.
Use maximum_significant_digits to increase calculation speed where desired. The lower the number used, the faster the calculation.
num can accept cells with both numbers and text.
num can accept cells with text formatted with the local currency symbol and thousands separators, and negatives can be formatted with either a leading hyphen or parentheses.
You can use the results of xlPrecision functions as the operands in other xlPrecision formulas without losing any precision, but using them as operands in Excel's arithmetic functions will truncate them to 15 significant digits.
If the return value is so large that it has more than 32,767 characters to the left of the decimal, then xlPrecision is of course unable to return a correct value and instead returns "#VALUE!". Note, that's a vastly larger number than Excel can return without xlPrecision. Excel itself can only return or recognize a number with no more than 308 digits to the left of the decimal.
Decimal symbols, thousands separators, and currency symbols are all localized. This means that an xlPrecision formula that returns "$1,234,567.89" in the USA will return "1.234.567,89 €" in Germany, "1 234 567,89 €" in France, "1 234 567.89 kr" in Estonia, and "1.234.567,89Lek" in Albania.
The 32,767 SD edition can only provide a maximum of 32,767 total characters, including all formatting characters such as decimal, leading hyphen or parentheses for negatives, and thousands separators. As a result, it can only return the maximum 32,767 significant digits when the result is an unformatted positive integer. This is due to Excel's limitation of 32,767 characters in a cell. In all cases, the 32,767 SD edition will give you as many significant digits as possible with the formatting you have chosen.
Depending on how many significant digits the edition of xlPrecision provides, the result may be too long to conveniently view. You can view the full result by right-clicking the cell and choosing Format Cells | Alignment | Wrap Text, and widening the column to the width of the screen. An easy way to view the full result without changing column widths or wrapping text is to right-click the cell, choose Copy, and then paste into Notepad or a word processor.
|=xlpFACTDOUBLE(6)||6 x 4 x 2||48|
|=xlpFACTDOUBLE(5)||5 x 3 x 1||15|
|=xlpFACTDOUBLE(5.9)||5 x 3 x 1||15|
|=xlpFACTDOUBLE(-4)||Negative num is invalid||#NUM!|
|=xlpFACTDOUBLE(9999)||Num over 9,273 is invalid||#NUM!|