%s=importdata('disp_data.dat'); %save the contents in displacement_data.dat as s
clear all;close all;clc
load disp_data

time=trace_x(1,:)'; %first column in data is saved as time
d_data=trace_y(2,:)';%second column in data is saved as experimental displacements
%maxval=max(d_data');
vval = max(d_data)
index=find(d_data==vval)
time=time(index:end,1)-time(index,1); %first column in data is saved as time
d_data=d_data(index:end);
% d_data(1)=d_data(1);
C0=3;
K0=2;
q0=[C0;K0];
% q0=[C0;K0;vval];
tic
[q,cost]=fminsearch(@cost_beam,q0,[],time,d_data);%find optimal parameters
toc
% options=optimset('');
%tic
%%[q1,cost1]=fminunc(@cost_beam,q0,[],time,d_data);%find optimal parameters
%toc
%pause
C=q(1);%optimal values for C and K
K=q(2);
% x0=[q(3) 0]; %initial conditions
x0=[d_data(1) 0]; %initial conditions
[t,x]=ode23(@ode_model,time,x0,[],C,K); %solve the mass-spring dashpot model
d_model=x(:,1);
subplot(2,1,1)
plot(time,d_data,'--',time, d_model,'r')
legend('experimental data','model displacement')
title('Two-parameter model estimation');
xlabel('time (s)');
ylabel('displacement');
subplot(2,1,2)
plot(time,(d_data-d_model))
title('Residuals');
legend('y_i-\hat{y}_i');
xlabel('time (s)');
ylabel('Error term');