how do I generate a spiral matrix which starts from first element

Question

Hatake nara 2019-6-9

0
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https://ww2.mathworks.cn/matlabcentral/answers/466188-how-do-i-generate-a-spiral-matrix-which-starts-from-first-element

评论： Arshub 2022-5-16

there is a command which takes only one arguement as a dimension of a square spiral matrix.But I need a way to generate such a matrix which takes the numbers of rows and columns as inputs and it might not be a square

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darova 2019-6-9

I don't understand. How this matrix should looks like? Can you please show some scheme?

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Answer 1

PIYUSH AGGARWAL 2019-6-9

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https://ww2.mathworks.cn/matlabcentral/answers/466188-how-do-i-generate-a-spiral-matrix-which-starts-from-first-element#answer_378439

编辑：PIYUSH AGGARWAL 2019-6-10

在 MATLAB Online 中打开

You will have to write your own code for this.

A = zeros(3,6);%You can change this mxn to whatever dims you like, be it square(m=n) or rectangular matrix.
[m,n] = size(A);
%m = no of rows
%n = no of columns
%A = matrix to be filled with spiral values
 %This code works fine. I commented an eg also below
top = 1;
bottom = m;
left = 1;
right = n; %To keep track of the four directions
value = 1;%Let us strat from 1
while true
    %Top Row First
    if left>right
        break;
    end
    for i = left:right
        A(top,i) = value;
        value = value + 1;
    end
    top = top + 1;
    %Then The RightMost Column
    if top>bottom
        break;
    end
    for i = top:bottom
        A(i,right) = value;
        value = value + 1;
    end
    right = right - 1;
    %Then Bottom Row
    if left>right
        break;
    end
    for i = right:-1:left
        A(bottom,i) = value;
        value = value + 1;
    end
    bottom = bottom - 1;
    %Then The Left Column
    if top>bottom
        break;
    end
    for i = bottom:-1:top
        A(i,left) = value;
        value = value + 1;
    end
    left = left + 1;
end
A