How to Create Functions to Calculate 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:

Creating a Function Macro

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. 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.