VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   4635
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4680
   LinkTopic       =   "Form1"
   ScaleHeight     =   4635
   ScaleWidth      =   4680
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   3000
      TabIndex        =   0
      Top             =   3960
      Width           =   1215
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Private Sub Command1_Click()
    'PROGRAM D3R1
    'Driver for routine TRAPZD
    NMAX = 14
    PIO2 = 1.5707963
    A = 0#
    B = PIO2
    Print
    Print Tab(5); "Integral of FUNC with 2^(n-1) points"
    Print Tab(5); "Actual value of integral is: ";
    Print Tab(35); Format$((FINT(B) - FINT(A)), "0.####00")
    Print
    Print Tab(5); "     n    Approx.Integral"
    For I = 1 To NMAX
        Call TRAPZD(A, B, S, I)
        Print Tab(10); Format$(I, "##");
        Print Tab(17); Format$(S, "0.####00")
    Next I
End Sub
Function FUNC(X)
    FUNC = (X ^ 2) * (X ^ 2 - 2#) * Sin(X)
End Function
Function FINT(X)
    'Integral of FUNC
    AAA = 4# * X * (X ^ 2 - 7#) * Sin(X)
    FINT = AAA - (X ^ 4 - 14# * X ^ 2 + 28#) * Cos(X)
End Function
Sub TRAPZD(A, B, S, N)
    If N = 1 Then
        S = 0.5 * (B - A) * (FUNC(A) + FUNC(B))
        IT = 1
    Else
        IT = 2 ^ (N - 2)
        TNM = IT
        DEL = (B - A) / TNM
        X = A + 0.5 * DEL
        Sum = 0#
        For J = 1 To IT
            Sum = Sum + FUNC(X)
            X = X + DEL
        Next J
        S = 0.5 * (S + (B - A) * Sum / TNM)
    End If
End Sub