help with using the "pmt function" - Xtreme Visual Basic Talk

01-13-2003, 07:05 PM

Andy H

Guest

Posts: n/a

help with using the "pmt function"

I'm writing a program to figure monthly payments. I have to use the pmt function. I keep getting a run time error 5. Invalid procedure call or argument. When I hit debug it points to this line.

Code:

Payment = Pmt(APR / 12, TotPmts, -PVal)

Any help would be appreciated.
Here is all of my code for this program.

Code:

Option Explicit

Private Sub cmdCalc_Click()
Dim PVal As Double, APR As Double
Dim TotPmts As Double, Payment As Double

Select Case lstInterest.ListIndex
    Case 0
        APR = 7
    Case 1
        APR = 7.25
    Case 2
        APR = 7.5
    Case 3
        APR = 7.75
    Case 4
        APR = 8
    Case 5
        APR = 8.25
    Case 6
        APR = 8.5
    Case 7
        APR = 8.75
    Case 8
        APR = 9
    Case 9
        APR = 9.25
    Case 10
        APR = 9.5
    Case 11
        APR = 9.75
    Case 12
        APR = 10
    Case 13
        APR = 10.25
    Case 14
        APR = 10.5
    Case 15
        APR = 10.75
    Case 16
        APR = 11
    Case 17
        APR = 11.25
    Case 18
        APR = 11.5
    Case 19
        APR = 11.75
    Case 20
        APR = 12
End Select
Payment = 0
TotPmts = 12
PVal = Val(txtPrincipal.Text)

If APR > 1 Then
    APR = APR / 100
ElseIf optTerm(0).Value = True Then
    TotPmts = 24
ElseIf optTerm(1).Value = True Then
    TotPmts = 36
ElseIf optTerm(2).Value = True Then
    TotPmts = 48
ElseIf optTerm(3).Value = True Then
    TotPmts = 60
End If

Payment = -Pmt(APR / 12, TotPmts, PVal)
lblPayment.Caption = Payment
End Sub

Private Sub Form_Load()
    frmMthlyPay.Left = (Screen.Width - frmMthlyPay.Width) / 2
    frmMthlyPay.Top = (Screen.Height - frmMthlyPay.Height) / 2
    lstInterest.AddItem "7%"
    lstInterest.AddItem "7.25%"
    lstInterest.AddItem "7.50%"
    lstInterest.AddItem "7.75%"
    lstInterest.AddItem "8%"
    lstInterest.AddItem "8.25%"
    lstInterest.AddItem "8.50%"
    lstInterest.AddItem "8.75%"
    lstInterest.AddItem "9%"
    lstInterest.AddItem "9.25%"
    lstInterest.AddItem "9.50%"
    lstInterest.AddItem "9.75%"
    lstInterest.AddItem "10%"
    lstInterest.AddItem "10.25%"
    lstInterest.AddItem "10.50%"
    lstInterest.AddItem "10.75%"
    lstInterest.AddItem "11%"
    lstInterest.AddItem "11.25%"
    lstInterest.AddItem "11.50%"
    lstInterest.AddItem "11.75%"
    lstInterest.AddItem "12%"
End Sub

Private Sub mnuFileExit_Click()
    Unload Me
End Sub

Private Sub mnuFilePrint_Click()
    PrintForm
End Sub

Private Sub mnuFormatBackground_Click()
    dlgCommon.Color = frmMthlyPay.BackColor
    dlgCommon.ShowColor
    frmMthlyPay.BackColor = dlgCommon.Color
    
End Sub

Private Sub mnuFormatFont_Click()
    dlgCommon.FontName = lblPayment.FontName
    dlgCommon.FontBold = lblPayment.FontBold
    dlgCommon.FontItalic = lblPayment.FontItalic
    dlgCommon.FontSize = lblPayment.FontSize
    
    dlgCommon.ShowFont
    
    lblPayment.FontName = dlgCommon.FontName
    lblPayment.FontBold = dlgCommon.FontBold
    lblPayment.FontItalic = dlgCommon.FontItalic
    lblPayment.FontSize = dlgCommon.FontSize
End Sub

Private Sub mnuFormatInfo_Click()
    dlgCommon.Color = fraInfo.BackColor
    dlgCommon.ShowColor
    fraInfo.BackColor = dlgCommon.Color
    
End Sub

Last edited by Andy H; 01-13-2003 at 08:28 PM.

01-13-2003, 07:47 PM

Iceplug

MetaCenturion

Retired Moderator
* Guru *

Join Date: Aug 2001

Location: California, USA

Posts: 16,583

Your TotPmts value is probably zero. Perhaps you should set it to 12 instead of 0 before the PVal = Val(txtPrincipal.Text)

Also, you can set the If blocks like

Code:

If ... Then
  ...
ElseIf ... Then
  ...
End If

instead of
If ... Then
  ...
Else
  If ... Then
    ...
  End If
End If

__________________

Iceplug, USN
Quadrill 1 Quadrill 2 (full) Quadrill 3 JumpCross .NET Website is ALIVE! - DL Platform Tour for VB.NET! Posting Guidelines Hint: Specify your location in your user cp profile if you want compassion!

01-13-2003, 08:11 PM

Andy H

Guest

Posts: n/a

Thanks Iceplug! that fixed it. Is using the select case like above the correct way to get the interest from the list box?

Last edited by Andy H; 01-13-2003 at 08:23 PM.

01-14-2003, 06:54 AM

Iceplug

MetaCenturion

Retired Moderator
* Guru *

Join Date: Aug 2001

Location: California, USA

Posts: 16,583

Well, there's no "correct" way of getting the interest, just as long as it works. However, a Select Case would be OK in situations like this... however, you could convert this into an 'expression' to get the APR from the ListIndex (where both are numbers and both increase in a linear fashion i.e. 7,7.25,7.5 going up by 0.25)
such as the expression APR = 0.25 * lstInterest.ListIndex + 7.