running a code on all columns

Consider, Y is a 1000 by 100 matrix...100 columns and 1000 rows

Y1=Y(:,1);

if I run this code

S1  = numel(Y1);
xx1 = reshape(Y1(1:S1 - mod(S1, 20)), 20, []);

if I run this code

xx1 is a 20 by 50 matrix

What code can I use to do the same thing for the remaining 99 columns of Y

Answer 1

[KSSV]

Y = rand(1000,100) ; 
iwant = zeros(20,50,100) ; 
for i = 1:100
    Y1 = Y(:,i) ;
    S1  = numel(Y1);  % this is same always 1000
    iwant(:,:,i) = reshape(Y1(1:S1 - mod(S1, 20)), 20, []);
end

With out loop

% no loop
m = 1000 ; 
n = mod(m,20) ; 
P = Y(1:m-n,:) ; 
Q = reshape(P,20,50,[]) ; 

[DARLINGTON ETAJE]

Thank You the loop works...

[DARLINGTON ETAJE]

Asking the question further:

Consider, Y is a 1000 by 100 matrix...100 columns and 1000 rows

Y1=Y(:,1);

if I run this code

S1  = numel(Y1);
xx1 = reshape(Y1(1:S1 - mod(S1, 20)), 20, []);
y1  = sum(xx1, 1).' / 20;

y1 is a 50 by 1 matrix

assuming z is also a 50 by 1 matrix

subtr=abs(y1-z)

What code can I use to do the same thing for the remaining 99 columns of Y

[KSSV]

If you want same to repeat for every column ..you can run a loop...but there are options to avoid looping.