clc
clear
%a)
load m44.dat
A = m44(:);     %zvektorizuje maticu
mesh(m44)   %vykresli trojrozmerny graf

%b)
priemer = mean(A)     %aritmeticky priemer
med = median(A)   %median
modus = mode(A)     %modus
n = size(A,1);  %urci pocet prvkov matice
sigma = sqrt(sum((A-mean(A)).^2)/(n-1.46))  %standardna odchylka, inak std()
gamma1 = sum((A-mean(A)).^3)/n/sigma^3      %sikmost, inak skewness()
gamma2 = (n+1)/(n-1)*sum((A-mean(A)).^4)/n/sigma^4-3    %spicatost, inak kurtosis()
sikmost = skewness(A)
spicatost = kurtosis(A)

%c)
sigma_r = 1.482*median(abs(A-median(A)))    %robustna odchylka
stars = find(abs(m44-median(A))>3.5*sigma_r);   %vrati vektor suradnic matice m44, v ktorych su odlahle body - hviezdy
noise = m44;
noise(stars) = [];  %odstrani prvky matice noise, kde sa nachadzaju hviezdy
A = noise;
priemer = mean(A)
med = median(A)
modus = mode(A)
sigma = sqrt(sum((A-mean(A)).^2)/(n-1.46))
gamma1 = sum((A-mean(A)).^3)/n/sigma^3
gamma2 = (n+1)/(n-1)*sum((A-mean(A)).^4)/n/sigma^4-3