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im stuck on making a layered matrix

Asked by Tristan Murphy on 3 May 2019
Latest activity Commented on by Tristan Murphy on 3 May 2019
function surround = surroundWith(a,b)
%function will take a given matrix 'a' and create a ring of numbers 'b' around
%it
surround = zeros(size(a,1)+2,size(a,2)+2); %sets the size of the matrix after the numbers b has been placed around 'a'
for ii = 1:size(a,1)+2
for jj = 1:size(a,2)+2
if (ii == 1 || ii == size(a,1)+2 || jj == 1 || jj == size(a,2)+2)
surround(ii,jj) = b; %setting the ring of pre-allocated zeros around 'a' to be 'b'
end
end
end
for kk = 1: size(a,1)
for ll = 1:size(a,2)
surround(kk+1,ll+1) = a(kk,ll);%setting the zeros within b to the numbers stored in 'a' at the corresponding locations
end
end
end
% if a = [1,2,3:4,5,6], and b = 5 the matrix should come out as:
5 5 5 5 5
5 1 2 3 5
5 4 5 6 5
5 5 5 5 5
im attempting to recreate this using only one parameter and to create a matrix with a 1 at the centre with a ring of numbers layered on top of eachother, increasing in value up to 'b' as the distance from the centre increases so:
%so layeredMatrix(5) should output:
5 5 5 5 5 5 5 5 5
5 4 4 4 4 4 4 4 5
5 4 3 3 3 3 3 4 5
5 4 3 2 2 2 3 4 5
5 4 3 2 1 2 3 4 5
5 4 3 2 2 2 3 4 5
5 4 3 3 3 3 3 4 5
5 4 4 4 4 4 4 4 5
5 5 5 5 5 5 5 5 5
ive been having a lot of trouble with this and would appriciate any help

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1 Answer

Answer by Geoff Hayes
on 3 May 2019
 Accepted Answer

Tristan - why not use a for loop
surround = 1;
for k = 2:5
surround = surroundWith(surround, k);
end

  5 Comments

no, as far as i know we are supposed to use our previous solution as a hint (which is the surroundWith function). in the description it does say this solution would be very helpful, and does not specify that we are not allowed to call it. however I do wish to find a method in which i can make the layered matrix without the requirement of calling the surroundWith function. either way i appriciate the help.
since you are told that this solution would be very helpful then I don't understand why you can't use it. :)
function layered = makelayered(a)
layered = 1;
for k = 2:a
layered = surroundWith(layered, k);
end
end
alrighty thanks for all the help :)

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