How to plot the phase portrait of a second-order differential equation? I cannot use quiver

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𝑥̈+ 𝑥̇ − 𝑥 − 𝑥 2 = 0
b. 𝑥̈+ 4𝑥̇ + 4𝑥 = 0
c. 𝑥̈− 2𝑥̇ + 2𝑥 = −8
d. 𝑥̈− 2𝑥 − 𝑥̇ − 2 = 0
I need to plot the phase portrait of these systems. What is wrong?
syms t
syms x(t)
dx=diff(x);
d2x=diff(x,2);
eq=d2x+dx-x-x.^2==0;
t=linspace(-1,1,100);
for n=1:5
s1=dsolve(eq,x(0)==n,dx(0)==n);
s2=diff(s1);
s1=subs(s1);
s2=subs(s2);
plot(s1,s2);
hold on
n=n+1;
end

Accepted Answer

SaiDileep Kola
SaiDileep Kola on 26 Feb 2021
Check the answer on similar question answered here

More Answers (1)

Shadaab Siddiqie
Shadaab Siddiqie on 26 Feb 2021
From my understanding you want to plot symbolic equation. Please refer ezplot which might help you.

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