close all;
clc;
file_name = 'W0009.dat';
[lam, I] = read_spectrum(file_name);
lam = lam*1e-3;
figure(1)
plot(lam,I);hold on;

M =50;
fs=10000; %Sampling Frequency
f1=0.5/(fs/2); %First Cutoff Frequency
f2=1000/(fs/2);%Second Cutoff Frequency
b = fir1(M,[f1, f2],'bandpass');
I1 = I;
I1 = filter(b, 1, I1); I1(1 : end - floor(M/2)) = I1(floor(M/2) + 1 : end);
I1 = filtfilt(b, 1, I1);
plot(lam,I1);hold on;