如何在Julia的Plots库中创建朝下的花括号？

要让已创建的贝塞尔曲线花括号朝下，无需复杂旋转操作，只需对曲线的y坐标做垂直镜像翻转（围绕目标水平线topy）即可。以下是修改后的完整代码：

using Plots, LaTeXStrings, InverseFunctions
gr()

x = collect(range(0, 4, length= 100))
f(x) = sqrt(4x)
g(x) = (4x - 4)/3

function Area(f, a, b, n)
    xs = a:(b-a)/n:b
    deltas = diff(xs)
    cs = xs[1:end-1]
    sum(f(cs[i]) * deltas[i] for i in 1:length(deltas))
end

r1 = round(Area(y -> (3y + 4 - y^(2))/(4), -1, 4, 50000), digits=5)

plot(g,-1,4, xtick=-1:1:4, xlims=(-1,4), ylims=(-2,4), 
    framestyle=:zerolines,
    label=L"g: 4x - 3y = 4", legend=:topleft)
plot!(f,-1,4, xtick=-1:1:4, xlims=(-1,4), ylims=(-2,4), 
    framestyle=:zerolines,
    label=L"f: y^{2} = 4x ", legend=:topleft)

plot!(x, f, fillrange = g, fillalpha = 0.35, c = 1, 
    label = L"f - g = y^{2} - 3y - 4 = 0", legend=:topleft)

plot!([0.42,1.95],[f(0.42),g(1.95)], label="", linecolor=:green)
plot!([0.3,1.8],[f(0.3),g(1.8)], label="", linecolor=:green)

annotate!([(0.27,1.27, (L"△ y", 8, :blue))])
annotate!([(1.95,0.97, (L"y_{i}", 8, :blue))])
annotate!([(2.13,1.17, (L"y_{i+1}", 8, :blue))])

annotate!([(1.41,1.9, (L" \frac{3y+4}{4} - \frac{y^{2}}{4}", 6, :blue))])

# 创建朝下的花括号
topy = 1.5
# 定义垂直镜像翻转函数，围绕topy水平线翻转
flip_y(y) = 2*topy - y

# 左半括号：将原朝上的凸起y坐标翻转
bezxl = [0.143239π, 0.143239π, 0.3851545π, 0.3851545π] 
bezyl = [flip_y(2), topy, flip_y(2), topy]
curves!(bezxl, bezyl; linecolor=:blue, label="")

# 右半括号：同理翻转y坐标
bezxr = [0.3851545π, 0.3851545π, 0.62707π, 0.62707π]
bezyr = [topy, flip_y(2), topy, flip_y(2)]
curves!(bezxr, bezyr; linecolor=:blue, label="")

# 在Julia REPL中输入r1可查看面积近似值

修改说明： #

1. 垂直镜像翻转：通过flip_y(y) = 2*topy - y函数，将原曲线中朝上的凸起（y=2）翻转到topy水平线的下方（y=1），直接实现括号朝下的效果，比旋转操作更精准。
2. 简化图例：移除了括号的label，避免图例冗余。
3. 坐标对齐：保持x坐标不变，仅调整y坐标，确保括号与原标注的水平线对齐。

内容的提问来源于stack exchange，提问作者Freya the Goddess