what is the probleme exactly u must be of size[3,20] but i find it [3,1]

function [u] = suite(A,b,u1,nb) 
    [n,n] = size(A);
    u=u1;
    for i = 1 : nb 
        u= A*u +b;
    end 
end 



A=[5/8 -1/4 1/8;1/4 0 1/4;1/8 -1/4 5/8];b=[1;-1;1];u1=[5;2;-4];m=20;p=m;
u=suite(A,b,u1;b)

[KSSV]

for i = 1 : nb    % this is meaning less, note that nb is a vector

Answer 1

[Jan]

Let me guess boldly: You want:

A = [5/8, -1/4, 1/8; 1/4, 0, 1/4; 1/8, -1/4, 5/8];
b = [1;-1;1];
u = [5; 2; -4];
m = 20;
u = suite(A, b, u, m)

function u = suite(A, b, u, m) 
    for i = 1 : m 
        u = A*u + b;
    end 
end 

[KARIM MANSOUR]

yes jan but at the result u must be size [3,20]