clc
clear
syms t;

taxis=6;
yaxis=10;
A=0;
B=1;
C=2;
i1=8;
i2=4;
cons=6;

xt1=cons;
funca1=sym('k');
x1=A*diff(funca1,'t',2)+B*diff(funca1,'t',1)+C*funca1;
b='x1=cons';
b=char(subs(b));
k=solve(b,'k');
yf=subs(funca1)


f='A*D2y+B*Dy+C*y=xt1';
f=char(subs(f));
ini1='y(0)=i1';
ini1=char(subs(ini1));
ini2='Dy(0)=i2';
ini2=char(subs(ini2));
if i2~=0&A~=0
y=dsolve(f,ini1,ini2);
else y=dsolve(f,ini1);
end

y=subs(y)
 
yn=y-yf
f0='A*D2y+B*Dy+C*y=0';
f0=char(subs(f0));
ini1='y(0)=i1';
ini1=char(subs(ini1));
ini2='Dy(0)=i2';
ini2=char(subs(ini2));
if i2~=0&A~=0
yzi=dsolve(f0,ini1,ini2);
else
    yzi=dsolve(f0,ini1);
end

yzi=subs(yzi)
yzs=y-yzi

subplot(2,3,1)
ezplot(y,[0,10]);
grid 
title('全響應')
axis([0,taxis,0,yaxis])
subplot(2,3,2)
t=0:0.1:10;
subs(y)
ezplot(yf,[0,10]);
grid 
title('受迫響應')
axis([0,taxis,0,yaxis])
subplot(2,3,3)
ezplot(yn,[0,10]);
grid 
title('自然響應')
axis([0,taxis,0,yaxis])
subplot(2,3,4)
ezplot(yzi,[0,10]);
grid 
title('零輸入響應')
axis([0,taxis,0,yaxis])
subplot(2,3,5)
ezplot(yzs,[0,10]);
grid 
title('零狀態響應')
axis([0,taxis,0,yaxis])