Reshuffled stack data plot

Hi

I am doing seismology plot. I have magnitudes(Y) and time(X). My magnitude changes from 1.1 till 4. Time in years 1969-2015.(3and 4-coloms in attached file)

I need to take all magnitudes bigger or equal 3 and look at how many points I have before and after 60 days from the Mag>=3 points. (all magnitudes should be taken in 120 days).

I tryed to solve it. I think it has 25 Magnitude >= 3 points and looked at how many magnitudes I have before and after 60 days from the mag >=3. Noticingly Magnitudes should be reshuffled.(it should not be original magnitudes). Finally I should stack all the 25 points results in one plot. I wrote code,it is working but not correct. I should not get peak at zero day. What would be my mistake?

Thanks!

[NUMERIC,TXT,RAW]=XLSREAD('oneLshock.xlsx'); x=NUMERIC(:,2); y=NUMERIC(:,1); Mag=NUMERIC(:,3);

for iii=1:length(TXT); date_str(iii,:)=TXT(iii,4); end

date_num=datenum(date_str,'dd/mm/yyyy');

date1=datenum('01/01/1955','dd/mm/yyyy'); date2=datenum('01/01/2016','dd/mm/yyyy');

A=-0.59; B=43.45; L=0.09; x11=A-L; x22=A+L; y11=B-L; y22=B+L;

Mag=Mag(randperm(length(Mag))); condition = ( Mag >= 3 & x > x11 & x < x22 & y > y11 & y < y22 & date_num > date1 & date_num < date2);

shock = zeros(121,1); date_num_diff = date_num(condition); for i=1:length(date_num_diff) ddi = date_num - date_num_diff(i); k = (ddi <= 60 & ddi >= -60); k60 = ddi(k); for ki = 1:length(k60) shock(k60(ki)+61)= shock(k60(ki)+61) + 1; end end

plot(-60:60,shock,'r'); xlabel('Time(days)','fontweight','bold','fontsize',10); ylabel('Numbers(M>3)','fontweight','bold','fontsize',10); title('Lacq 1L shocks','fontweight','bold','fontsize',10); grid on;