calling multiple functions .m files

Hi there, i'm trying to simulate an earthquake shaking a structure. The earthquake signal generated by calling a separate function -and i've got this bit working, but i'm trying to call that signal into a function for the structure as: x'' = - earthquake - 2.eta.w.x' - w^2.x and then call that function using the ode45 solver. But i can't get this bit to work :( Would appreciate if someone can take a look at what i've done wrong (the stuff below where it says "CALLING FUNCTION" is the file I run for the simulation.

Thanks!

function dxdt = sdof(t,x)

t = [0:0.005:60];
eta = 0.05;    
omega = 2*pi/0.15; 

f = linspace(0,4,2048);
zeta = 0.3;
sigma = 0.3; 
fn = 5; 
T90 = 0.3; 
eps = 2; 
tn = 20;
[y,t] = kanai_tajimi_run(sigma,fn,zeta,f,T90,eps,tn);

earthquake = [y,t];

        dxdt = [x(2);
                - earthquake - 2*eta*omega*x(2) - omega^2*x(1)]; 
  end

-----------------------
CALLING FUNCTION
_______________________

close all;clc;

[t,x] = ode45(@sdof,[0 60],[0; 0]);

plot(t,x)
title('Isolated structure response to MCE');
xlabel('Time (t)');
ylabel('Response (m, m/s)');
legend('Displacement (m)','Velocity (m/s)');
grid on;

[Walter Roberson]

[y,t] = kanai_tajimi_run(...)

Why are you overwriting the input parameter t ? That is, at the very least, confusing to the readers.