Not enough input arguments.

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

Answer 1

[Walter Roberson]

Other than having to fix the for being on the same line, it looks okay to me.

suitem(rand(8,8), rand, rand, 7)

ans = 8×8

5.9738 5.7873 6.4540 5.8167 5.9296 5.6976 6.9287 6.5290 6.3011 6.1045 6.8077 6.1355 6.2547 6.0097 7.3086 6.8868 6.9830 6.7651 7.5445 6.7995 6.9317 6.6601 8.0996 7.6322 6.8662 6.6519 7.4183 6.6857 6.8157 6.5487 7.9641 7.5045 7.3179 7.0894 7.9063 7.1255 7.2641 6.9795 8.4879 7.9982 7.8525 7.6073 8.4838 7.6460 7.7947 7.4894 9.1080 8.5824 5.8720 5.6887 6.3441 5.7176 5.8287 5.6005 6.8108 6.4178 5.0072 4.8508 5.4098 4.8755 4.9704 4.7757 5.8077 5.4726

●

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

[KARIM MANSOUR]

thank you walter

[KARIM MANSOUR]

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)

u must be size [3,20] but i found it [3,1] please help

[Walter Roberson]

Why would it be 3 x 20? You create m=20 and you assign that to p, but you do not use m or p in the code.

%{
u=suite(A,b,u1;b)
%}

That is invalid syntax. Assuming you want

%{
u=suite(A,b,u1,b)
%}

then notice that you are passing b twice, and that the second one is in a place you expect a scalar.

I suspect what you want is

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, m)

u = 3×20

5.0000 3.1250 2.9688 3.0859 3.1934 3.2593 3.2953 3.3141 3.3236 3.3285 3.3309 3.3321 3.3327 3.3330 3.3332 3.3333 3.3333 3.3333 3.3333 3.3333 2.0000 -0.7500 -0.5625 -0.0781 0.2617 0.4561 0.5593 0.6125 0.6395 0.6530 0.6598 0.6633 0.6650 0.6658 0.6662 0.6665 0.6666 0.6666 0.6666 0.6667 -4.0000 -1.3750 0.7188 1.9609 2.6309 2.9780 3.1547 3.2437 3.2885 3.3109 3.3221 3.3277 3.3305 3.3319 3.3326 3.3330 3.3332 3.3332 3.3333 3.3333

●

function [u] = suite(A,b,u1,nb) 
    [n,n] = size(A);
    u = u1(:);
    for i = 2 : nb 
        u(:,i) = A * u(:,i-1) + b;
    end 
end 

[KARIM MANSOUR]

thank you this is what i want

[KARIM MANSOUR]

Walter,check please https://fr.mathworks.com/matlabcentral/answers/716073-hilbert-matrix-come-on