XL98: Function to Convert Degree to/from Fractions of Degrees

ID: Q192367

The information in this article applies to:

Microsoft Excel 98 Macintosh Edition

SUMMARY

Fractions of a degree are commonly expressed in units called minutes and seconds. One degree is equivalent to 60 minutes, and similarly, one minute equals 60 seconds. These units are most commonly used for expressing a navigational point such as a point on a nautical chart.

Although Microsoft Excel 98 Macintosh Edition lacks a built-in number format to express these terms, this article contains a sample custom function you can use to convert a degree value (stored in decimal format, or base 10) to degrees, minutes, and seconds (stored in text format). Also, this article contains a user-defined function that converts degrees, minutes, and seconds (stored in text format) to a degree value (stored in decimal format).

MORE INFORMATION

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Converting Decimal Degrees to Degrees/Minutes/Seconds

The following Microsoft Visual Basic for Applications custom function accepts an angle formatted as a decimal value and convert it to a text value displayed in degrees, minutes, and seconds.

   Function Convert_Degree(Decimal_Deg) As Variant
       With Application
           'Set degree to Integer of Argument Passed
           Degrees = Int(Decimal_Deg)

           'Set minutes to 60 times the number to the right
           'of the decimal for the variable Decimal_Deg
           Minutes = (Decimal_Deg - Degrees) * 60

           'Set seconds to 60 times the number to the right of the
           'decimal for the variable Minute
           Seconds = Format(((Minutes - Int(Minutes)) * 60), "0")

           'Returns the Result of degree conversion
           '(for example, 10.46 = 10~ 27  ' 36")
           Convert_Degree = " " & Degrees & "~ " & Int(Minutes) & "' " _
               & Seconds + Chr(34)

       End With

   End Function

To use this function, create a conversion formula, as in the following example:

   =Convert_Degree(10.46)

This formula will return 10~ 27' 36" (that is, 10 degrees, 27 minutes, 36 seconds).

Converting Degrees/Minutes/Seconds to Decimal Degrees

The following Microsoft Visual Basic for Applications custom function accepts a text string of degrees, minutes and seconds formatted in the exact same format that the Convert_Degree function returns (for example, 10~ 27' 36") and converts it to an angle formatted as a decimal value. This is exactly the reverse of the Convert_Degree custom function.

WARNING: This custom function fails if the Degree_Deg argument does not follow the format of the following:

   <degrees>~ <minutes>' <seconds>"

as stated earlier.

Function Convert_Decimal(Degree_Deg As String) As Double

   ' Declare the variables to be double precision floating-point.
   Dim degrees As Double
   Dim minutes As Double
   Dim seconds As Double

   ' Set degree to value before "~" of Argument Passed.
   degrees = Val(Left(Degree_Deg, InStr(1, Degree_Deg, "~") - 1))

   ' Set minutes to the value between the "~" and the "'"
   ' of the text string for the variable Degree_Deg divided by
   ' 60. The Val function converts the text string to a number.
   minutes = Val(Mid(Degree_Deg, InStr(1, Degree_Deg, "~") + 2, _
             InStr(1, Degree_Deg, "'") - InStr(1, Degree_Deg, _
             "~") - 2)) / 60

    ' Set seconds to the number to the right of "'" that is
    ' converted to a value and then divided by 3600.
    seconds = Val(Mid(Degree_Deg, InStr(1, Degree_Deg, "'") + _
            2, Len(Degree_Deg) - InStr(1, Degree_Deg, "'") - 2)) _
            / 3600

   Convert_Decimal = degrees + minutes + seconds

End Function

To use this function, create a conversion formula, as in the following example:

   =Convert_Degree("10~ 27' 36""")

This formula will return 10.46 (that is, 10.46 degrees).

NOTE: You are required to type three quotation marks (""") at the end of argument of this formula to balance the quotation mark for the seconds and the quotation mark for the text string.

Additional query words: XL98

Keywords          : kbdta kbdtacode 
Version           : MACINTOSH:98
Platform          : MACINTOSH
Issue type        : kbhowto

Last Reviewed: May 18, 1999