shark

local xratio = 10.0
local yratio = 10.0
local number = 10000
local wmin = 1.0
local hmin = 1.0
local detalization = 1000

local wmax = wmin * xratio
local hmax = hmin * yratio

local points = {}
for i = 0, detalization do
    local xi = i * wmax / detalization
    table.insert(points, {xi, 0.0})
end
for i = 1, number do
    local w = wmin + (wmax - wmin) * math.random()
    local h = hmin + (hmax - hmin) * math.random()
    local l = (wmax - w) * math.random()
    local r = l + w
    local mean = (l + r) / 2.0
    for _, point in ipairs(points) do
        if l <= point[1] and point[1] <= r then
            local y
            if point[1] < mean then
                local x = (point[1] - l) / (mean - l)
                y = math.sqrt((2.0 - x) * x)
            else
                local x = (point[1] - mean) / (r - mean)
                y = 1.0 - math.sqrt((2.0 - x) * x)
            end
            point[2] = point[2] + y * h
        end
    end
end

local gnuplot = io.popen('gnuplot', 'w')
gnuplot:write('reset;\n')
gnuplot:write('set terminal wxt 1;\n')
gnuplot:write(string.format('set xrange [%f:%f];\n', 0.0, wmax))
gnuplot:write(string.format('set yrange [%f:%f];\n', 0.0, hmax * number))
gnuplot:write('set size square;\n')
gnuplot:write(string.format('set xtics %f;\n', wmax / 10.0))
gnuplot:write(string.format('set ytics %f;\n', hmax * number / 10.0))
gnuplot:write('set grid xtics ytics;\n')
gnuplot:write('plot "-" using 1:2 notitle with lines;\n')
for _, point in ipairs(points) do
    gnuplot:write(string.format('%f %f\n', point[1], point[2]))
end
gnuplot:write('e\n')
gnuplot:flush();

os.execute('pause');
gnuplot:write('exit\n');
gnuplot:flush();
gnuplot:close()