Newton Method error.

Philosophaie · Aug 28th 2015

[INDENT]Getting an error on the line where you calculate "diff".
I am certain the equations are correct.

E1 is in Radians and MA(k) and EA(k) are in Degrees.
e(k) is no Units.

Error code:

Quote

Invalid procedure call or argument.

Code:

Code

'Newton Method
	    Dim e(1000) As Double, MA(1000) As Double
            Pi = Application.WorksheetFunction.Pi
            E1 = Pi / 4 'Initialize
            diff = 1 'Initialize
            Do Until Math.abs(diff) < 0.00001
                If E1 = 3 * Pi / 2 Then
                    MsgBox ("/0")
                    E1 = 0.1
                End If
                diff = (E1 - e(k) * Math.Sin(E1) - MA(k) * Pi / 180) / (1 + Math.Cos(E1)) 'Error on this line
                E1 = E1 + diff
            Loop
            EA(k) = E1 * 180 / Pi

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What am I doing wrong?[/INDENT]

cytop · Aug 28th 2015

Re: Newton Method error.

Untested Observation...

That "Math.Sin(E1).." and the corresponding call to "Math.Cos..." look like they're trying to reference the .NET System.Math Namespace but you have not included anything to show that your project has a reference to that Namespace.

You could try using the Excel Worksheet Functions SIN() & COS() - just replace the 'Math.' with 'WorksheetFunction.'

**pike** · Aug 28th 2015

Re: Newton Method error.

hello,

the arrays MA(k) and e(k) is empty

Philosophaie · Aug 28th 2015

Do Loop are changing inside the Loop itself

I think the reason this will not work is the variables for the Do Loop are changing inside the Loop itself and Excel does not like that.
Is there any other Loops that may work in this case?

Code

E1 = Pi / 4 'Initialize
            diff = 1 'Initialize
            Do While Math.Abs(diff) > 0.00001
                diff = (E1 - e(k) * Math.Sin(E1) - MA(k) * Pi / 180) / (1 + Math.Cos(E1))
                E1 = E1 + diff
            Loop

Tried

Code

Do Until Math.Abs(diff) < 0.00001
                 diff = (E1 - e(k) * Math.Sin(E1) - MA(k) * Pi / 180) / (1 + Math.Cos(E1))
                 E1 = E1 + diff
             Loop

Code

Do
                diff = (E1 - e(k) * Math.Sin(E1) - MA(k) * Pi / 180) / (1 + Math.Cos(E1))
                E1 = E1 + diff
            Loop While Math.Abs(diff) > 0.00001

A For or a ForEach will not work in this case.

**pike** · Aug 28th 2015

Re: Newton Method error.

what are the values in arrays MA(k) and e(k) ?

Newton Method error.

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