# Matlab question, very stuck

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James Harrison on 10 Jan 2021
Commented: Image Analyst on 11 Jan 2021
I am very stuck with this question, any help would be appreciated.
function [New_Matrix] = sequence_matrix(n)
%UNTITLED4 Summary of this function goes here
% Detailed explanation goes here
if n ==1
v=2
elseif n==2
v=3
elseif n>=3
i(n) = 2*v(n-1) + 3*v(n-2)
i=zeros(n,n);
m = i;
i(1:n+1:end) = v
end

Image Analyst on 10 Jan 2021
Close but not quite. Try it this way:
function [New_Matrix] = sequence_matrix(n)
% Detailed explanation goes here
New_Matrix = zeros(n);
v = 2;
if n >= 2
v = [2, 3];
end
if n >= 3
for k = 3 : n
v(k) = 2*v(k-1) + 3*v(k-2)
end
end
for k = 1 : n
New_Matrix(k, k) = v(k);
end
end
##### 2 CommentsShowHide 1 older comment
Image Analyst on 11 Jan 2021
At the beginning, after you assign New_Matrix, say
if n < 2
warningMessage = sprintf('Error. Invalid input.\nYou entered n = %d.\nn must be 2 or greater', n);
uiwait(errordlg(warningMessage));
return;
end

William on 10 Jan 2021
Your program seems to be a little uncertain about whether v is a number or a vector, and it also doesn't assign the values correctly into the diagonal of the matrix i(). However, the general sequence of operations is correct. Let me suggest the following:
1. Create the vector v as a vector with n elements, using v = zeros(1,n);
2. Fill in the values of v(j), with v(1) = 2, v(2) = 3, and v(j) = 2*v(j-1) + 3*v(j-2) for all j > 2;
3. Then put the values of v into the diagonal of a matrix I using I = diag(v);
Let me know how it turns out!

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