XL: How to Create Functions to Calculate Light Years

ID: Q142152

The information in this article applies to:

Microsoft Excel for Windows, versions 5.0, 5.0c
Microsoft Excel for Windows NT, version 5.0
Microsoft Excel for Windows 95, versions 7.0, 7.0a
Microsoft Excel 97 for Windows
Microsoft Excel for the Macintosh, versions 5.0, 5.0a
Microsoft Excel 98 Macintosh Edition

SUMMARY

Microsoft Excel does not include a function that will convert miles into light years or light years to miles. However, you can use the following formulas for this calculation

   Miles to Light Years = M / 5,877,000,000,000

   Light Years to Miles = LY * 5,877,000,000,000

where M is the number of miles and LY is the number of light years.

MORE INFORMATION

Suppose you want to calculate the number of miles between the earth and the closest star system, Alpha Centauri. Alpha Centauri is 4.3 light years away.

The following formula typed into a cell on a worksheet, using the information above, will return a grand total of 25,271,100,000,000 miles:

   =4.3*5,877,000,000,000

Creating a Function Macro

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals 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 needs. If you have limited programming experience, you may want to contact the Microsoft fee-based consulting line at (800) 936-5200. For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

   http://www.microsoft.com/support/supportnet/refguide/

To create this function using Visual Basic for Applications, enter the following in a new Visual Basic module:

   Function LightYearsToMiles(LY) As Double
       Dim Convert As Double
       Convert = 5877000000000
       'Defines variables
       LightYearsToMiles = LY * Convert 'Performs computation
   End Function

   Function MilesToLightYears(M) As Double
       Dim Convert As Double
       Convert = 5877000000000
       'Defines variables
       MilesToLightYears = M / Convert 'Performs calculation
   End Function

To use the custom function, follow these steps:

1. Type the following in a worksheet:

      A1: 4.3
      A2: =LightYearsToMiles(A1)
      A3: =MilesToLightYears(A2)

2. The total number of miles, located in cell A2, between Earth and Alpha

   Centauri is 25,271,100,000,000 miles. The number of light years,
   located in cell A3, is 4.3.

3. Format cell A2 with the following format code: ###,###,###,###,###.

   To do this, select the Format menu, and choose Cells, the Number tab
   and Custom.

REFERENCES

"Visual Basic User's Guide," version 5.0, Chapter 3, "Creating a User-Defined Function"

Additional query words: 5.00 5.00a 5.00c 7.00 7.00a 97 98 XL98 XL97 XL7 XL5

Keywords          : xlformula 
Version           : MACINTOSH:; WINDOWS:; winnt:
Platform          : MACINTOSH WINDOWS winnt
Issue type        : kbhowto

Last Reviewed: May 17, 1999