d8r3.txt

VB常用数值算法集 内含有解线性代数方程组

Private Sub Command1_Click()
    'PROGRAM D8R3
    'Driver for routine TRED2
    NP = 3
    Dim A(3, 3), C(3, 3), D(3), E(3), F(3, 3)
    A(1, 1) = 1#: A(1, 2) = 2#: A(1, 3) = 3#
    A(2, 1) = 2#: A(2, 2) = 2#: A(2, 3) = 3#
    A(3, 1) = 3#: A(3, 2) = 3#: A(3, 3) = 3#
    For I = 1 To NP
        For J = 1 To NP
            C(I, J) = A(I, J)
        Next J
    Next I
    Call TRED2(C(), NP, D(), E())
    Print
    Print Tab(5); "Diagonal elements"
    Print Tab(5)
    For I = 1 To NP
        Print Format$(D(I), "#.000000"),
    Next I
    Print Tab(5)
    Print Tab(5); " 'Off-diagonal elements"
    Print Tab(5)
    For I = 2 To NP
        Print Format$(E(I), "#.000000"),
    Next I
    'Check transformation matrix
    For J = 1 To NP
        For K = 1 To NP
            F(J, K) = 0#
            For L = 1 To NP
                For M = 1 To NP
                    F(J, K) = F(J, K) + C(L, J) * A(L, M) * C(M, K)
                Next M
            Next L
        Next K
    Next J
    'How does it look?
    Print Tab(5)
    Print Tab(5); "Tridiagonal matrix"
    Print Tab(5)
    For I = 1 To NP
        For J = 1 To NP
            Print Format$(F(I, J), "0.000000"),
        Next J
        Print
    Next I
End Sub