how would i type in my fraction in the polynomial to find my real and complex roots

Question

adriana resendez 2015-3-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/181867-how-would-i-type-in-my-fraction-in-the-polynomial-to-find-my-real-and-complex-roots

回答： Star Strider 2015-3-6

   fx = x^5-((x^4)/2)-2x^3-x^2-3
roots = fx

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2015-3-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/181867-how-would-i-type-in-my-fraction-in-the-polynomial-to-find-my-real-and-complex-roots#answer_170342

在 MATLAB Online 中打开

I expanded your function in the Symbolic Math Toolbox, and got the coefficient vector:

cfx = [1     -0.5       -2       -1        0       -3];
fxroots = roots(cfx)

produces:

fxroots =
       1.9710e+000 +             i
      -1.1131e+000 +654.8187e-003i
      -1.1131e+000 -654.8187e-003i
     377.6052e-003 +877.5463e-003i
     377.6052e-003 -877.5463e-003i

Note that the first root is real. It should be simply 1.9710, but since the others are complex, it is listed with a complex part for consistency. You could do all of this in the Symbolic Math Toolbox of course, but since you didn’t mention that you have access to it, I do not assume you do.