I have a user defined VB function, which i want to do in MATLAB, i know its interpolation but not able to figure out, which function will perfectly fit it.

I have a piece of code on the excel in VB, which is named as L_invert, the same function i want to write it in MATLAB, i know its interpolation but not able to figure out, which would fit it (PFA example), i tried that example in that VB user defined function, it gives the output(PFA excel).

User Defined function in VB:

Public Function l_invert(ByVal Table As Object, ByVal X_value As Double, _

ByVal y_value As Double)

Dim i As Integer ' counter.

Dim x0, x1, y0, y1 As Integer ' Table lookup indices

Dim x0wt, x1wt, y0wt, y1wt As Double ' weighting factors

Dim r, c As Integer ' number of rows and columns

'Formulas below determine the number of rows and columns in the table

r = Table.Rows.Count - 1

For i = 2 To Table.Rows.Count

If IsEmpty(Table.Cells(i, 1)) Or Not IsNumeric(Table.Cells(i, 1)) Then

r = i - 2

Exit For

End If

Next i

c = Table.Columns.Count - 1

For i = 2 To Table.Columns.Count

If IsEmpty(Table.Cells(1, i)) Or Not IsNumeric(Table.Cells(1, i)) Then

c = i - 2

Exit For

End If

Next i

'Check for bad input

If c <= 1 Or r <= 1 Then

l_invert = [#value]

Exit Function

End If

If Table.Cells(1, 2).Value > X_value Then

x0 = 1

x1 = 1

x0wt = 1

x1wt = 0

End If

If Table.Cells(1, c + 1).Value < X_value Then

x0 = c

x1 = c

x0wt = 1

x1wt = 0

End If

'Fill out x-values if nothing is selected

If IsEmpty(x0) Then

x0 = 1

x1 = 1

x0wt = 1

x1wt = 0

For i = 1 To c - 1

If Table.Cells(1, i + 1) <= X_value And Table.Cells(1, i + 2) >= X_value Then

x0 = i

x1 = i + 1

x1wt = (X_value - Table.Cells(1, i + 1).Value) / (Table.Cells(1, i + 2).Value - Table.Cells(1, i + 1).Value)

x0wt = 1 - x1wt

Exit For

End If

Next i

End If

'Check for out of range low

If ((Table.Cells(2, x0 + 1).Value * x0wt) + (Table.Cells(2, x1 + 1).Value * x1wt)) > y_value Then

l_invert = Table.Cells(2, 1).Value

Exit Function

End If

'Check for out of range high

If ((Table.Cells(r + 1, x0 + 1).Value * x0wt) + (Table.Cells(r + 1, x1 + 1).Value * x1wt)) <= y_value Then

l_invert = Table.Cells(r + 1, 1).Value

Exit Function

End If

For i = 1 To r - 1

If ((Table.Cells(i + 1, x0 + 1).Value * x0wt) + (Table.Cells(i + 1, x1 + 1).Value * x1wt)) <= y_value And ((Table.Cells(i + 2, x0 + 1).Value * x0wt) + (Table.Cells(i + 2, x1 + 1).Value * x1wt)) >= y_value Then

y0 = i

y1 = i + 1

y1wt = (y_value - ((Table.Cells(i + 1, x0 + 1).Value * x0wt) + (Table.Cells(i + 1, x1 + 1).Value * x1wt))) / (((Table.Cells(i + 2, x0 + 1).Value * x0wt) + (Table.Cells(i + 2, x1 + 1).Value * x1wt)) - ((Table.Cells(i + 1, x0 + 1).Value * x0wt) + (Table.Cells(i + 1, x1 + 1).Value * x1wt)))

y0wt = 1 - y1wt

Exit For

End If

Next i

l_invert = Table.Cells(y0 + 1, 1) * y0wt + Table.Cells(y1 + 1, 1) * y1wt

End Function