Returns the double factorial of a number.
| Name | Type | Description |
| arg1 | any | Is the value for which to return the double factorial. |
builder.CreateFile("xlsx");
var oWorksheet = Api.GetActiveSheet();
var oFunction = Api.GetWorksheetFunction();
oWorksheet.GetRange("A1").SetValue(oFunction.FACTDOUBLE(123));
builder.SaveFile("xlsx", "FACTDOUBLE.xlsx");
builder.CloseFile();