dsolve error (simultaneous differential equations)

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Seungwon Lee
Seungwon Lee 2020-5-18
评论： Seungwon Lee 2020-5-18
clear all
close
clc
m = 10;
k = 1000;
u0 = 0.01;
syms y1 y2
f=dsolve('m*D2y1+2*k*y1-k*y2==0,m*D2y2-k*y1+2k*y2==0','y1(0)==0,Dy1(0)==0,Dy2(0)==0,y2(0)==0.01');
figure
ezplot(f,[0 100]);
I want to solve simultaneous differential equation but i have a problem solving it.
Can someone help me find whats causing error?

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采纳的回答

Sulaymon Eshkabilov
Here is the answer:
clear all
close
clc
m = 10;
k = 1000;
u0 = 0.01;
syms y1(t) y2(t)
Dy1=diff(y1);
Dy2=diff(y2);
D2y1=diff(y1, 2);
D2y2=diff(y2, 2);
Eqn1=m*D2y1+2*k*y1-k*y2;
Eqn2=m*D2y2-k*y1+2*k*y2;
ICs=[y1(0)==0,Dy1(0)==0,Dy2(0)==0,y2(0)==0.01];
f=dsolve(Eqn1,Eqn2, ICs);
figure
ezplot(f.y1,[0 100]), hold on
ezplot(f.y2, [0, 100]), legend('y_1(t)', 'y_2(t)', 'location', 'best')
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Sulaymon Eshkabilov
Sulaymon Eshkabilov 2020-5-18
There two different ways of expressing ODE expressions. This is one of them and is the logically structured one. The other one is direct that you define your variable without specifying to differentuiate it w.r.t what variable that may create a problem in cases when there is an obscurity with the existing variables in your MATLAB workspace.
Good luck

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