my cord for ordinary differential equation didn't work

hi. i just entered ordinary differential equation for analysising for damping by coulomb friction.

but it didn't work. just start, and happened nothing. i tried to find where is wrong, but i couldn't.

can you help me?

that is my code.

tspan = [0: 0.05: 8];

x0 = [0.4; 0.0];

[t,x] = ode23('dfuncl', tspan, x0);

plot (t, x(:, 1));

xlabel ('t');

ylabel ('x(t)');

%dfuncl.m

function f = dfuncl(t,x)

f = zeros(2,1);

f(1) = x(2);

f(2) = -0.5 * 9.81 * sign(x(2)) - 100 * x(1) / 5;

Answer 1

[Star Strider]

Try this instead:

tspan = [0: 0.05: 8];
x0 = [0.4; 0.0];
[t,x] = ode15s(@dfuncl, tspan, x0);

figure
plot (t, x(:, 1));
xlabel ('t');
ylabel ('x(t)');

%dfuncl.m
function f = dfuncl(t,x)
f = zeros(2,1);
f(1) = x(2);
f(2) = -0.5 * 9.81 * sign(x(2)) - 100 * x(1) / 5;
end

The differential encounters a singularity and throws this Warning:

Warning: Failure at t=7.022881e-01.  Unable to meet integration tolerances without reducing the
step size below the smallest value allowed (1.776357e-15) at time t. 

.