d4r32.frm

VB常用数值算法集 内含有解线性代数方程组

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   6240
   ClientLeft      =   1665
   ClientTop       =   750
   ClientWidth     =   5460
   LinkTopic       =   "Form1"
   ScaleHeight     =   6240
   ScaleWidth      =   5460
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   3720
      TabIndex        =   0
      Top             =   5400
      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 D4R32
    'Driver for routine PLGNDR
    Open "D:\VB常用数值算法集\DATA\FNCVAL.DAT" For Input As #1
    Do
      Line Input #1, Text$
    Loop While Text$ <> "Legendre Polynomials"
    Line Input #1, NVAL$
    NVAL = Val(NVAL$)
    Print Text$
    Print
    Print "   N     M          X          Actual       PLGNDR(N,B)"
    For I = 1 To NVAL
        Line Input #1, DUM$
        N = Val(Mid(DUM$, 1, 6))
        M = Val(Mid(DUM$, 7, 6))
        X = Val(Mid(DUM$, 13, 12))
        ACTUAL = Val(Mid(DUM$, 25))
        FAC = 1
        If M > 0 Then
            For J = N - M + 1 To N + M
                FAC = FAC * J
            Next J
        End If
        FAC = 2 * FAC / (2 * N + 1)
        ACTUAL = ACTUAL * Sqr(FAC)
        Print Tab(4); Format$(N, "#0");
        Print Tab(10); Format$(M, "#0");
        Print Tab(15); Format$(X, ".##0000E+00");
        Print Tab(29); Format$(ACTUAL, ".000000E+00");
        Print Tab(43); Format$(PLGNDR(N, M, X), ".000000E+00")
    Next I
    Close #1
End Sub
Function PLGNDR(L, M, X)
    If M < 0 Or M > L Or Abs(X) > 1# Then Print "bad arguments"
    PMM = 1#
    If M > 0 Then
        SOMX2 = Sqr((1# - X) * (1# + X))
        FACT = 1#
        For I = 1 To M
            PMM = -PMM * FACT * SOMX2
            FACT = FACT + 2#
        Next I
    End If
    If L = M Then
        PLGNDR = PMM
    Else
        PMMP1 = X * (2 * M + 1) * PMM
        If L = M + 1 Then
            PLGNDR = PMMP1
        Else
            For LL = M + 2 To L
                PLL = X * (2 * LL - 1) * PMMP1 - (LL + M - 1) * PMM
                PLL = PLL / (LL - M)
                PMM = PMMP1
                PMMP1 = PLL
            Next LL
            PLGNDR = PLL
        End If
    End If
End Function