计算分段函数：y=6x*x+9x-7 (x大于等于0时)；y=3x*x+4x-5 (x小于0时)

function Fun(x)
if x < 0 then
Fun = 3 * x * x + r * x - 5
else
Fun = 6 * x * x + 9 * x - 7
end if
end function