d2r3.txt

来自「VB常用数值算法集 内含有解线性代数方程组」· 文本 代码 · 共 26 行

Private Sub Command1_Click()
    'PROGRAM D2R3
    'DRIVER for routine SPLINE
    N = 20
    PI = 3.1415926
    Dim X(20), Y(20), Y2(20)
    Print
    Print Tab(5); "Second-derivative for sin(x) from 0 to PI"
    '生成插值数组
    For I = 1 To 20
        X(I) = I * PI / N
        Y(I) = Sin(X(I))
    Next I
    '用三次样条函数计算二阶导数
    YP1 = Cos(X(1))
    YPN = Cos(X(N))
    Call SPLINE(X(), Y(), N, YP1, YPN, Y2())
    '验证计算结果
    Print Tab(5); "            spline        actual"
    Print Tab(5); " angle     2nd deriv     2nd deriv"
    For I = 1 To N
        Print Tab(6); Format$(X(I), "##.##");
        Print Tab(16); Format$(Y2(I), "##.#####0");
        Print Tab(30); Format$(-Sin(X(I)), "##.#####0")
    Next I
End Sub