Inaccuracy of .AnglefromAxis method | angle by two points

[Anonymous]

Hi, I am drawing a line using two known point coords.

p1(5411906,88685 | 5813796,25171)

p2(5411721,72968|5813830,60112)

Then I calculate the angle of the line using .AnglefromAxis method.

Somehow there is an inaccuracy between the angle given by the properties window by AutoCAD[349.4902603] (Picture) and the angle calculated [349,362793485571 ]. This is crucial for my main program, so do I have to deal with this inaccuracy or is there a mistake in logic ?

I am thankful for any ideas.

Sub angle()

Dim angle As Double
Dim p1(2) As Double
Dim p2(2) As Double

p1(0) = 5411906.88685
p1(1) = 5813796.25171
p2(0) =5411721.72968
p2(1) =5813830.60112

angle = ThisDrawing.Utility.AngleFromXAxis(p1, p2)
angle = angle * 180 / 3.xxx-xxxxxxxx

Debug.Print angle

ThisDrawing.SendCommand "line" & vbCr & "5411906.88685,5813796.25171" & vbCr & "

5411721.72968,5813830.60112" & vbCr & vbCr

End Sub

[Norman_Yuan · Accepted solution]

Are you serious? Or are you using "FAKE" AutoCAD? Kidding.

As programmer myself, I can imagine how difficult to write code to deliberately generate "inaccurate" result for a simple math calculation. 

Anyway, I cannot reproduce the inaccuracy as you described with following code:

Option Explicit

Public Sub angle()

    Dim angle As Double
    Dim p1(2) As Double
    Dim p2(2) As Double
    
    p1(0) = 5411906.88685
    p1(1) = 5813796.25171
    p2(0) = 5411721.72968
    p2(1) = 5813830.60112
    
    angle = ThisDrawing.Utility.AngleFromXAxis(p1, p2)
    angle = angle * 180 / 3.1415926
    MsgBox angle

    Dim line As AcadLine
    Set line = ThisDrawing.ModelSpace.AddLine(p1, p2)
    line.Update
    MsgBox line.angle * 180 / 3.1415926

    '' This would result in the same angle
    ThisDrawing.SendCommand _
        "line" & vbCr & _
        "5411906.88685,5813796.25171" & vbCr & _
        "5411721.72968,5813830.60112" & vbCr & vbCr
    
End Sub

By the way, When post code, please use the button "</>" on toolbar above the input window, so that the code would be easier to read.

It is strange you hide the PI value you used as "3.xxx-xxxx" in your code. So, my guess would be that the only reason your code's calculation is wrong is because you used WRONG PI value, which should be 3.1415926...

[Anonymous]

I just tried to reproduce the inaccuracy at home (Acad2017), no inaccuracy in sight. At work I am using Acad2015, shouldn't make a difference, right? I'll try to reproduce again at work tomorrow.

Thanks for the advice about posting code right, I'll try to use it next time.

By using Ctrl + C and Ctrl + V somehow my "pi" got transformed from 3,xxx-xxxxxxxx to 3.xxx-xxxxxxxx.