# MATLAB: Columns of a matrix

codecolumnsmatrix

I would like to know how to achieve one by one the columns of a matrix. Let me put here what I have done:
 %COMBINATION OF ONE VARIABLE.
%we first read all the variables
Nby=53 ; % Le nombre des variables mesurées
y = xlsread('C:\Users\p105312\Desktop\dig+echg+washer+evap.xlsx' ,'E14:E66' ); % Les valeurs des variables mesurées
Nbz=5; % Le nombre des variables non mesurées
z =xlsread('C:\Users\p105312\Desktop\dig+echg+washer+evap.xlsx' ,'E75:E79' ); % Une estimation de la variable non mesurée extraite de la simulation
Nbc=15 ; % Le nombre de contraintes de systéme
Cp = xlsread('C:\Users\p105312\Desktop\dig+echg+washer+evap.xlsx' ,'D89:D94' ); % Les capacités calorifiques
y = xlsread('C:\Users\p105312\Desktop\dig+echg+washer+evap.xlsx' ,'E14:E66' ); % Les valeurs des variables mesurées
 Ay = [       1,       1,       1,       1,       -1,       -1,       -1,       -1,       0,        1,        1,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ; Cp(2)*y(12), Cp(4)*y(13), Cp(5)*y(14), Cp(3)*y(15), -Cp(5)*y(16), -Cp(3)*y(17), -Cp(5)*y(18), -Cp(5)*y(19),       0,  Cp(5)*y(21),  Cp(5)*y(22), Cp(2)*y(1), Cp(4)*y(2), Cp(5)*y(3), Cp(3)*y(4), -Cp(5)*y(5), -Cp(3)*y(6), -Cp(5)*y(7), -Cp(5)*y(8),      0,  Cp(5)*y(10),  Cp(5)*y(11), 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       1,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        1,        1,       0,       -1,       -1,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;      0,       0,       0,       0,        0,        0,  Cp(5)*y(18),  Cp(5)*y(19), Cp(2)*y(20), -Cp(5)*y(21), -Cp(5)*y(22),      0,      0,      0,      0,       0,       0,  Cp(5)*y(7),  Cp(5)*y(8), Cp(2)*y(9), -Cp(5)*y(10), -Cp(5)*y(11), 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        1,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 1, 1, 1,  -1, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   1, 1,  -1,   -1, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    1, 1, 1, 1, -1,   -1, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;      0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    1, 1, 1, 1, 1, 1,   -1,   0,    0,    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0, y(41), 0, -z(4), -y(42), 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0, y(26), -y(29),    0,    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,  y(42), 0, 0, 0,  0, -y(43), 0, 0, 0, 0, 0,    0,   0,  y(29), -y(34),    0,       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,  y(43), 0, 0, 0, 0, 0, -y(44),   0,    0,  y(34), -y(40),       0,       0,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        1,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       0,      -1,        0,        0,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0,       1,       1,       -1,       -1,       0,       0,       0,        0,        0       ;       0,       0,       0,       0,        0,        0,        0,        0,       0,        0,        0,      0,      0,      0,      0,       0,       0,       0,       0,      0,        0,        0, 0, 0, 0,   0, 0,   0,    0, 0, 0, 0,  0,    0, 0, 0, 0, 0, 0,    0,   0,    0,    0,    0, Cp(2)*y(49), Cp(5)*y(50), -Cp(1)*y(52), -Cp(5)*y(53), Cp(2)*y(45), Cp(5)*y(46), -Cp(2)*z(5), -Cp(1)*y(47), -Cp(5)*y(48)];
%———————————-
for j=1:Nby,
    for i=1:Nbc,        A(i,j)=Ay(i,j);    end    Aend

A = [1 2 3;...     4 5 6;...     7 8 9]; A(:,1) = [1; 4; 7]A(:,2) = [2; 5; 8]