How to get the positive root of the cubic a*x^3+3*b*x^2+3*c*x+d=0

2013 4 17
3 个回答
回答已采纳
更新时间：2021 3 14
12 次查看（30 天）

0 个投票

How to get the positive root of the cubic a*x^3+3*b*x^2+3*c*x+d=0 where a=1,c=b+2, d=-3 and b=.1:.1:2.
If rr is the root, find rr/(rr+1) for each b.

请先登录，再回答此问题。

 采纳的回答

Kye Taylor
Kye Taylor 2013-4-17
编辑：Kye Taylor 2013-4-17

0 个投票

You can try
b = .1:.1:2;
a = 1;
c = b+2;
d = -3;
posR = zeros(1,length(b));
for i = 1:length(b)
r = roots([a,3*b(i),3*c(i),d]);
posR(i) = r(r>0); % only one real root for the values you specified
posR(i) = posR(i)/(posR(i)+1);
end

更多回答（2 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Multirate Signal Processing 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by