d2r4.txt

常用的数值算法的VB程序

Private Sub Command1_Click()
    'PROGRAM D2R4
    'DRIVER for routine SPLINT,which calls SPLINE
    NP = 10
    PI = 3.141593
    Dim XA(10), YA(10), Y2(10)
    For NFUNC = 1 To 2
        If NFUNC = 1 Then
            Print
            Print Tab(5); "Sine function from 0 to PI"
            For I = 1 To NP
                XA(I) = I * PI / NP
                YA(I) = Sin(XA(I))
            Next I
            YP1 = Cos(XA(1))
            YPN = Cos(XA(NP))
        ElseIf NFUNC = 2 Then
            Print
            Print Tab(5); "Exponential function from 0 to 1"
            For I = 1 To NP
                XA(I) = 1# * I / NP
                YA(I) = Exp(XA(I))
            Next I
            YP1 = Exp(XA(1))
            YPN = Exp(XA(NP))
        Else
            Stop
        End If
        'Call SPLINE to get second derivatives
        Call SPLINE(XA(), YA(), NP, YP1, YPN, Y2())
        'Call SPLINT for interpolations
        Print Tab(5); "   x            f(x)     interpolation"
        For I = 1 To 10
            If NFUNC = 1 Then
                X = (-0.05 + I / 10#) * PI
                F = Sin(X)
            ElseIf NFUNC = 2 Then
                X = (-0.05 + I / 10#)
                F = Exp(X)
            End If
            Call SPLINT(XA(), YA(), Y2(), NP, X, Y)
            Print Tab(7); Format$(X, "##.##0000");
            Print Tab(19); Format$(F, "##.###000");
            Print Tab(32); Format$(Y, "##.###000")
        Next I
        Print Tab(5); "**********************************"
    Next NFUNC
End Sub