Not able to plot a proper graph for the equation.

1 次查看（过去 30 天）

Kartikeya 2024-6-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2126596-not-able-to-plot-a-proper-graph-for-the-equation

评论： Kartikeya 2024-6-8

y = (1*1*((25)-(x.^2)))/((x.^4)-((x.^2)*((1*(1.78))+(25)+1))+(1*(25)));
fplot(y);
i used this code but am only getting a straight line instead of the 2 peak FRF that I want.

7 个评论
显示 5更早的评论隐藏 5更早的评论

Kartikeya 2024-6-8

@Torsten @Sam Chak Is it possible to get a graph like the following one for my case?

Kartikeya 2024-6-8

@Torsten @Sam Chak Thanks for the answers guys.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

John D'Errico 2024-6-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2126596-not-able-to-plot-a-proper-graph-for-the-equation#answer_1469026

编辑：John D'Errico 2024-6-8

在 MATLAB Online 中打开

syms x

y = (1*1*((25)-(x.^2)))/((x.^4)-((x.^2)*((1*(1.78))+(25)+1))+(1*(25)))

y =

First, where are the poles? A pole lives where the denominator is zero.

[N,D] = numden(y)

N =

D =

droot = solve(D)

droot =

double(droot)

ans = 4x1

0.9650 5.1816 -0.9650 -5.1816

So we need to look between -6 and 6.

fplot(y,[-6,6])

NO. It does not look the way you want it to look. But it is your function. You set the problem. If it does not look like what you want, then maybe you are starting with the wrong function.

3 个评论
显示 1更早的评论隐藏 1更早的评论

John D'Errico 2024-6-8

编辑：John D'Errico 2024-6-8

That could be. And you could have offered that as an answer. But my mind reading abilities are sometimes lacking, only answering the question posed, instead of answering a different question. If I always tried that, I'd end up chasing into infinitely many rabbit holes.

Kartikeya 2024-6-8

在 MATLAB Online 中打开

@Sam Chak @Torsten @John D'Errico Guys I got the whole thing. Just had to use the absolute values of the y variable that I got. Thanks for your help, all of you.

x = 0:0.1:10;
y = (1*1*((25)-(x.^2)))./((x.^4)-((x.^2)*((1*(1.78))+(25)+1))+(1*(25)));
plot(y);
xlim([0 100]);
ylim([0 inf]);
xlabel('Natural Frequency Ratio');
ylabel('Amplitude x_0');
z = abs(y);
disp(z);
plot(z);