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In Microsoft Excel, you can create custom Microsoft Visual Basic for Applications functions to perform calculations. By default, these custom functions are available to all worksheets in the workbook that contains the custom function. Therefore, you can call them just as you call built-in functions in Microsoft Excel. However, if you attempt to call a custom function from outside of the workbook that contains the code, you must first make a reference to the workbook that contains the custom function.
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. The following steps show you how to create a simple custom function, how to call the function from the workbook that contains the code, and how to call this custom function from another workbook.
To Create a Custom Function
To Call the Function from the Workbook That Contains the Function CodeTo call this function from within Test.xls, type the following formula in cell A1 on Sheet1:
=myfunction(3)Cell A1 should display the value 6, because the custom function doubled the value that was sent to it.
To Call the Function from Another WorkbookIn order to call the function from a workbook, you must create a reference to the workbook that contains the code. To create a reference, follow these steps:
=myfunction(5)Cell A1 should display the value 10.
NOTE: If the reference is not made as outlined in steps 1-4, cell A1 displays the #NAME? error value because Microsoft Excel does not know where to find the "myfunction" custom function. Naming the function and the project with the same name also results in the #NAME? error. Note also that you cannot create a reference to an unsaved workbook, so if you encounter an error when you try to create the reference, make sure the workbook that contains the custom function has been saved.
Excel 97For more information about custom functions, from the Visual Basic Editor, click Contents and Index on the Help menu, click the Index tab in Help, type the following text
function proceduresand then double-click the selected text to go to the "Writing a Function Procedure" topic. If you are unable to find the information you need, ask the Office Assistant.
Excel 98 Macintosh EditionFor more information about custom functions, from the Visual Basic Editor, click the Office Assistant, type function, click Search, and then click to view "Writing a Function Procedure."
Earlier Versions of ExcelFor more information about custom functions, click Answer Wizard on the Help menu and type:
tell me how to create a user-defined function
Article ID: 141288 - Last Review: October 11, 2006 - Revision: 2.3