ベクトルフローの流線を描く (格子座標).

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Sub Test_Plt_Streamplot1()
    Const N = 256
    Dim X(N - 1) As Double, Y(N - 1) As Double, Z(N - 1, N - 1) As Double
    Dim U(N - 2, N - 2) As Double, V(N - 2, N - 2) As Double
    Dim I As Integer, J As Integer
    '-- Make data
    Call Linspace(-3, 3, N, X())
    Call Linspace(-3, 3, N, Y())
    For I = 0 To N - 1
        For J = 0 To N - 1
            Z(I, J) = (1 - X(J) / 2 + X(J) ^ 5 + Y(I) ^ 3) * Exp(-X(J) ^ 2 - Y(I) ^ 2)
        Next
    Next
    For I = 0 To N - 2
        X(I) = X(I + 1)
        Y(I) = Y(I + 1)
        For J = 0 To N - 2
            U(I, J) = -Z(I + 1, J + 1) + Z(I, J + 1)
            V(I, J) = Z(I + 1, J + 1) - Z(I + 1, J)
        Next
    Next
    '-- Plot
    Call Plt.Streamplot1(N - 1, N - 1, X(), Y(), U(), V())
    Call Plt.Show
End Sub