d5r1.frm

常用的数值算法的VB程序

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   4845
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4020
   LinkTopic       =   "Form1"
   ScaleHeight     =   4845
   ScaleWidth      =   4020
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   2400
      TabIndex        =   0
      Top             =   4200
      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 D5R1
    'Driver for routine EULSUM
    NVAL = 40
    Dim WKSP(40)
    'Evaluate ln(1+x)=x-x^2/2+x^3/3-x^4/4... for -1<x<1
    Print
    Print Tab(5); "How many terms in polynomial?"
    'Input MVAL , between 1 and 40, MVAL=0 TO END
    MVAL = 20
    Print Tab(5); MVAL
    If (MVAL <= 0) Or (MVAL > NVAL) Then Exit Sub
    Print Tab(5); "  X        Actual      Polynomial"
    For I = -8 To 8 Step 1
        X = I / 10#
        SUM = 0#
        XPOWER = -1#
        For J = 1 To MVAL
            XPOWER = -X * XPOWER
            TERM = XPOWER / J
            Call EULSUM(SUM, TERM, J, WKSP())
        Next J
        Print Tab(4); Format$(X, ".##000");
        Print Tab(15); Format$(Log(1# + X), "#.###000");
        Print Tab(29); Format$(SUM, "#.###000")
    Next I
End Sub
Sub EULSUM(SUM, TERM, JTERM, WKSP())
    Static NTERM As Integer
    If JTERM = 1 Then
        NTERM = 1
        WKSP(1) = TERM
        SUM = 0.5 * TERM
    Else
        TMP = WKSP(1)
        WKSP(1) = TERM
        For J = 1 To NTERM
            DUM = WKSP(J + 1)
            WKSP(J + 1) = 0.5 * (WKSP(J) + TMP)
            TMP = DUM
        Next J
        If Abs(WKSP(NTERM + 1)) <= Abs(WKSP(NTERM)) Then
            SUM = SUM + 0.5 * WKSP(NTERM + 1)
            NTERM = NTERM + 1
        Else
            SUM = SUM + WKSP(NTERM + 1)
        End If
    End If
End Sub