回答（1 个）

Andrei Bobrov
Andrei Bobrov 2012-2-25

0 个投票

please read about function roots
or use function solve from Symbolic Math Toolbox
eg
use roots
%polynomial x^3-6*x^2-50*x-4
p = [1 -6 -50 -4]
out = roots(p)
use solve and Symbolic Math Toolbox
syms x
out2 = solve(x^3-6*x^2-50*x-4)
vpa(out2,6)
on Nasir comment
out = zeros(3,...);
for j1 = 1:....
B = ...
A = ...
out(:,j1) = roots([1, B-1, A-3*B^2, A*B-B^2-B^3]);
end

5 个评论
显示 3更早的评论 隐藏 3更早的评论

Nasir Qazi
Nasir Qazi 2012-2-25
if I have equation like this
Z^3 +(B-1)Z^2 +(A-3B^2)Z -(AB-B^2-B^3)=0
where the values of A & B are varies in iteration .
in that case how can I calculate the Roots ?
Walter Roberson
Walter Roberson 2012-2-25
Careful, there would be three roots for each cubic, so you would not be able to store the output of roots() in to a single array location out(j1)
Andrei Bobrov
Andrei Bobrov 2012-2-25
Thank you Walter! Corrected.
Nasir Qazi
Nasir Qazi 2012-2-27
I have a condition of trail and error which will repeat the process of roots find after a condition of error checking , but after 10 iteration it give me a error , root input cannot be inf or nan , where exactly do I have a fault in the coding ... ?
Walter Roberson
Walter Roberson 2012-2-27
I think we would need to see the code.

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Symbolic Math Toolbox 的更多信息

标签

提问:

Nasir Qazi
Nasir Qazi
2012-2-25

编辑：

Matt J
Matt J
2013-10-25

Community Treasure Hunt

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

Start Hunting!

Translated by