function [m,s]=marks(x) 
% [m,s]=marks(x) 
% x is a vector, m and s are scalars 
% the function computes the mean value m and standard deviation s
% of the data sample x 

n=length(x); 
m=sum(x)/n; % built-in function for the sum of omponents of a vector 
s=sqrt(sum((x-m).^2)/n); % componentwise operations 