Use VBA functions and variables in a spreadsheet - vba

Question

I'm new to Excel VBA. I am trying to use a VBA function I found online that enables the user to use goalseek on multiple cells at a time. How do I call the function in a spreadsheet and how do I point to the cells that are supposed to be associated with the variables in the function (e.g. Taddr, Aaddr, gval). Do I have to write the cell values and ranges in the code itself and just run it that way?
Maybe I should redefine the function so that it takes these variables as input, so I can write a formula like =GSeekA(Taddr,Aaddr,gval)
Option Explicit
Sub GSeekA()
Dim ARange As Range, TRange As Range, Aaddr As String, Taddr As String, NumEq As Long, i As Long, j As Long
Dim TSheet As String, ASheet As String, NumRows As Long, NumCols As Long
Dim GVal As Double, Acell As Range, TCell As Range, Orient As String
' Create the following names in the back-solver worksheet:
' Taddr - Cell with the address of the target range
' Aaddr - Cell with the address of the range to be adjusted
' gval - the "goal" value
' To reference ranges on different sheets also add:
' TSheet - Cell with the sheet name of the target range
' ASheet - Cell with the sheet name of the range to be adjusted
Aaddr = Range("aaddr").Value
Taddr = Range("taddr").Value
On Error GoTo NoSheetNames
ASheet = Range("asheet").Value
TSheet = Range("tsheet").Value
NoSheetNames:
On Error GoTo ExitSub
If ASheet = Empty Or TSheet = Empty Then
Set ARange = Range(Aaddr)
Set TRange = Range(Taddr)
Else
Set ARange = Worksheets(ASheet).Range(Aaddr)
Set TRange = Worksheets(TSheet).Range(Taddr)
End If
NumRows = ARange.Rows.Count
NumCols = ARange.Columns.Count
GVal = Range("gval").Value
For j = 1 To NumCols
For i = 1 To NumRows
TRange.Cells(i, j).GoalSeek Goal:=GVal, ChangingCell:=ARange.Cells(i, j)
Next i
Next j
ExitSub:
End Sub

Answer 1

GSeekA is a Subprocedure, not a Function. Subprocedures cannot be called from worksheet cells like Functions can. And you don't want to convert GSeekA into a function. Functions should be used to return values to the cell(s) from which they're called. They shouldn't (and often can't) change other things on the sheet.
You need to run GSeekA as a sub. Now the problem becomes how you get user provided information into the sub. You can use InputBox to prompt the user to enter one piece of information. If you have too many, InputBox becomes cumbersome.
You can create areas in the spreadsheet where the user must enter information, then read from that area. That's how it's set up now. It's reading cells named asheet and tsheet. As long as those named ranges are present, the code works.
Finally, you can create a UserForm that the user will fill out. That's like putting a bunch of InputBoxes on one form.
Update Here's a simple procedure that you can start with and enhance.
Public Sub GSeekA()
Dim rAdjust As Range
Dim rTarget As Range
Dim dGoal As Double
Dim i As Long
'Set these three lines to what you want
Set rAdjust = Sheet1.Range("I2:I322")
Set rTarget = Sheet1.Range("J2:J322")
dGoal = 12.1
For i = 1 To rAdjust.Count
rTarget.Cells(i).GoalSeek dGoal, rAdjust.Cells(i)
Next i
End Sub