Fractale de Mandelbrot sur Excel

Comment générer la fameuse fractale de Mandelbrot sur une feuille Excel

Scripts VBA

Sub drawMandelbrot()

Dim c As Variant

n = 201

xmax = 1.2

xmin = -1.2

ymax = 0.6

ymin = -1.5

For i = 1 To n

    For j = 1 To n

        c = WorksheetFunction.Complex((ymax - ymin) * (j - 1) / (n - 1) + ymin, (xmax - xmin) * (i - 1) / (n - 1) + xmin)

        Call iterate(c, Range("A1").Offset(i - 1, j - 1))

    Next

Next

End Sub

Sub iterate(c As Variant, cel As Range)

k = 1

cond = True

Z = 0

While cond = True

    'Zn+1=Zn^2+c

    Z = WorksheetFunction.ImSum(WorksheetFunction.ImProduct(Z, Z), c)

    If WorksheetFunction.ImAbs(Z) > 2 Then

        cond = False

    Else

        k = k + 1

    End If

    If k > 255 Then

        cond = False

        cel.Interior.Color = vbBlack

    End If

Wend

End Sub