I'm trying to plot differential equations but it's showing errors.

Here is the code.....

clc
clear all
close all
syms i(t)
di = diff(i);
d2i = diff(i,2);
z = dsolve((d2i+40*di+1000*i(t)) == 0.1*diff(heaviside(t)));
i(0)==4;
di(0)==15;
z1 = diff(z); % ANS OF BIT a

subplot(2,1,1)
ezplot(z)
title('STEP RESPONCE')
xlabel('time (t)');
ylabel('(z)');
grid on;
gtext('1841014009');

subplot(2,1,2)
ezplot(z1)
title('IMPLUSE RESPONCE')
xlabel('time (t)');
ylabel('(z1)');
grid on;
gtext('1841014009');

And here is the errors

Please help me to solve this problem

Answer 1

[Ameer Hamza]

You are not applying the initial condition with solving the ode. Check the following code

clc
close all
syms i(t)
di = diff(i);
d2i = diff(i,2);
cond = [i(0)==4; di(0)==15];
z = dsolve((d2i+40*di+1000*i(t)) == 0.1*diff(heaviside(t)), cond);
z1 = diff(z); % ANS OF BIT a

subplot(2,1,1)
fplot(z)
title('STEP RESPONCE')
xlabel('time (t)');
ylabel('(z)');
grid on;
gtext('1841014009');

subplot(2,1,2)
fplot(z1)
title('IMPLUSE RESPONCE')
xlabel('time (t)');
ylabel('(z1)');
grid on;
gtext('1841014009');

Also, fplot() is recommended instead of ezplot().

[Suraj Narayan]

it is still showing errors.

[Ameer Hamza]

Which MATLAB release are you using?

[Suraj Narayan]

2016a