d4r22.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    =   5430
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4500
   LinkTopic       =   "Form1"
   ScaleHeight     =   5430
   ScaleWidth      =   4500
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   375
      Left            =   2520
      TabIndex        =   0
      Top             =   4680
      Width           =   1335
   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 D4R22
    'Driver for routine BESSK0
    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$ <> "Modified Bessel Function K0"
    Line Input #1, NVAL$
    NVAL = Val(NVAL$)
    Print Text$
    Print
    Print "    X          Actual        BESSK0(X)"
    For I = 1 To NVAL
        Line Input #1, DUM$
        X = Val(Mid(DUM$, 1, 6))
        Value = Val(Mid(DUM$, 7))
        Print Tab(4); Format$(X, "#0.##");
        Print Tab(12); Format$(Value, ".0000000E+00");
        Print Tab(28); Format$(BESSK0(X), ".0000000E+00")
    Next I
    Close #1
End Sub
Function BESSK0(X)
    P1 = -0.57721566:      P2 = 0.4227842
    P3 = 0.23069756:       P4 = 0.0348859
    P5 = 0.00262698:       P6 = 0.0001075
    P7 = 0.0000074:
    Q1 = 1.25331414:       Q2 = -0.07832358:
    Q3 = 0.02189568:       Q4 = -0.01062446
    Q5 = 0.00587872:       Q6 = -0.0025154
    Q7 = 0.00053208
    If X <= 2# Then
        Y# = X * X / 4#
        BBB = Y * (P5 + Y * (P6 + Y * P7))
        AAA# = P1 + Y * (P2 + Y * (P3 + Y * (P4 + BBB)))
        BESSK0 = (-Log(X / 2#) * BESSI0(X)) + AAA#
    Else
        Y# = (2# / X)
        BBB = Y * (Q5 + Y * (Q6 + Y * Q7))
        AAA# = Q1 + Y * (Q2 + Y * (Q3 + Y * (Q4 + BBB)))
        BESSK0 = (Exp(-X) / Sqr(X)) * AAA#
    End If
End Function
   Function BESSI0(X)
      P1 = 1#
      P2 = 3.5156229
      P3 = 3.0899424
      P4 = 1.2067492
      P5 = 0.2659732
      P6 = 0.0360768
      P7 = 0.0045813
      Q1 = 0.39894228
      Q2 = 0.01328592
      Q3 = 0.00225319
      Q4 = -0.00157565
      Q5 = 0.00916281
      Q6 = -0.02057706
      Q7 = 0.02635537
      Q8 = -0.01647633
      Q9 = 0.00392377
      If Abs(X) < 3.75 Then
          Y = (X / 3.75) ^ 2
          AAA = Y * (P5 + Y * (P6 + Y * P7))
          BESSI0 = P1 + Y * (P2 + Y * (P3 + Y * (P4 + AAA)))
      Else
          AX = Abs(X)
          Y = 3.75 / AX
          AAA = Exp(AX) / Sqr(AX)
          BBB = Q4 + Y * (Q5 + Y * (Q6 + Y * (Q7 + Y * (Q8 + Y * Q9))))
          BESSI0 = AAA * (Q1 + Y * (Q2 + Y * (Q3 + Y * BBB)))
      End If
   End Function