2D ベクトル場の矢印を表示する (格子座標).

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Sub Test_Plt_Quiver1()
    Const M = 6, N = 6
    Dim X(N - 1) As Double, Y(M - 1) As Double
    Dim U(M - 1, N - 1) As Double, V(M - 1, N - 1) As Double
    Dim C(0, 0) As Long
    Dim I As Integer, J As Integer
    '-- Make data
    Call Linspace(-4, 4, N, X())
    Call Linspace(-4, 4, M, Y())
    For I = 0 To M - 1
        For J = 0 To N - 1
            U(I, J) = Y(I) + X(J)
            V(I, J) = Y(I) - X(J)
        Next
    Next
    '-- Plot
    Call Plt.Quiver1(N, M, X(), Y(), U(), V(), C(), "color='C0', angles='xy', scale_units='xy', scale=5, width=.015")
    Call Plt.Show
End Sub