clear  % finger in every pie (заниматься всем сразу)

% % follow the steps!!!
% create matrix (the simplest - using assignment):
A=[pi,pi/2 0.5, 0.3 sqrt(4); eps realmin (realmin)/eps 1:2]  % space (or) comma
B=[pi:pi/12:2*pi] % vector (as arithmetic progression)  [B0:stepB:Bend]      
realmin
realmax
eps
% type control
         isreal(A)  %explain...
         isfinite(A)        % result

% the main matrices constructors: 
a= eye(2,3) % identity matrix
            % zeros matrix
            % matrix elements are equal one

x=randi([-2,2],4,1) % random integer matrix
                    % uniformly distributed random matrix in the interval (0,1)

% editing matrices                    
a=[ones(3);eye(6,3);zeros(3)]; % concatenation
        spy(a,'r*',10) %  visualization nonzero elements by graph 
a(2:2:end)=0
spy(a)
% concatenation using function cat (examples for two directions):
                   % along row
                   % along column

% changing the shape of the matrix (explain):
arep=repmat(1:4,5,2)                   
ar=reshape (a,4,9)                   
% conditional assignment:
a(a>0)=3
a(a==0)=1

% deleting blocks:
a(5:end,:)=[]  % the last (end-5+1) lines (rows)
a(:,2)=[]      % the second column is deleted 
b=a'*x          % product of matrices, explain a'

% Creating special-type matrices:
D=diag(1:5)   % explain
dd=diag(a)
              % create  random matrix 8-order T
              % use for T function triu 
              % use for T function tril

% element-by-element operations on matrices:
d=a.^3 
c=a.*rand(size(a)) % eplain and ...
                   % add example for .\ 

% Workspace information
who
whos
% need to assign new variable with identificator mylogical value ans!
save ab a b
clear
load ab