can someone help with this error please

% Define the differential equation
f = @(t,x) x.^2 - t;

% Define the time interval and initial conditions
tspan = [0,2];
a1 = 0;
a2 = 0.75;

% Solve the differential equation using ode45
[t1,x1] = ode45(f,tspan,a1);
[t2,x2] = ode45(f,tspan,a2);

% Plot the solutions
hold on
plot(t1,x1,'b','LineWidth',2)
plot(t2,x2,'r--','LineWidth',2)
xlabel('t')
ylabel('x')
legend('a=0','a=0.75')

% Plot the distance between the trajectories
figure
plot(t1,abs(x1-x2),'k','LineWidth',2)

Arrays have incompatible sizes for this operation.

xlabel('t')
ylabel('|x1(t) - x2(t)|')

Answer 1

[Torsten]

Instead of

tspan = [0,2]

use

tspan = linspace(0,2,100)

This fixes the number of output times to 100 for both calls to ode45.

Answer 2

[Image Analyst]

x1 has 41 elements while x2 has 45 elements, so how can you subtract them?