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Computing angular errors in Excel

Computing angular errors in Excel

Computing angular errors in Excel

I am trying to create a Excel spreadsheet that will produce
the amount of error between expected and actual measurements. I am entering negative and positive numbers in a degree/minute/second format.


Expected results      Actual results       Error Amount
________________      ______________       ____________

Horizontal/Vertical   Horizontal/Vertical
-10 deg   / +35 deg   -10:20:10 / 34:54:10

RE: Computing angular errors in Excel

You can use VBA. Do a Split on your input cells, convert the parts to a Double, subtract. Then convert back to D:M:S format.

Here is a quick and dirty sample to get you started. You will of course need to add some error checking to ensure that there are 2 colons in each input cell! This takes first input from A1 <Cells(1, 1)> and C1 <Cells(1, 3)> and posts the result in E1.


Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim myDegree As Integer
Dim myMinute As Integer
Dim mySecond As Integer
Dim myStart
myStart = Split(Cells(1, 1), ":")
mystartangle = CDbl(myStart(0) + myStart(1) / 60 + myStart(2) / 3600)
Dim myEnd
myEnd = Split(Cells(1, 3), ":")
myendangle = CDbl(myEnd(0) + myEnd(1) / 60 + myEnd(2) / 3600)
mydiff = myendangle - mystartangle
mysign = Sgn(mydiff)
Debug.Print mysign
mydiff = Abs(mydiff)
myDegree = Int(mydiff)
myMinute = Int(60 * (mydiff - myDegree))
mySecond = Int(3600 * (mydiff - myDegree - myMinute / 60) + 0.5)
Cells(1, 5) = IIf(mysign = -1, "-", "") & CStr(myDegree) & ":" & (myMinute) & ":" & (mySecond)
End Sub

Good Luck
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RE: Computing angular errors in Excel

Why do you insist on that type of
degree call out?  What is wrong
with decimal degrees?

RE: Computing angular errors in Excel

It looks like your format is automatically getting set to h:mm:ss.  Use the '@' format to get the value in degrees (10:20:10 = 0.430671).  

Select the cell, <right-click><Format cells><custom><@>.  

If somehow you have a string of '10:20:10' use =value(10:20:10) to convert it back to a number.  

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