How do i use a pair of nested for loops to store a series of 9 related numbers in a 3x3 matrix?

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Sarah Mcmillan 2018-9-5

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https://ww2.mathworks.cn/matlabcentral/answers/417743-how-do-i-use-a-pair-of-nested-for-loops-to-store-a-series-of-9-related-numbers-in-a-3x3-matrix

编辑： James Tursa 2018-9-6

the outer loop decides what row and the inner loop decides what column to store each number in the series, the code should prompt the user for the starting number and increment of the series

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Sarah Mcmillan 2018-9-6

编辑：James Tursa 2018-9-6

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I'm sorry for the confusion, I'm just frustrated. I am trying to do a pair of nested loops so that I can just denote a as the number I want to start with and b the number I want to continuously add. In the end I want my matrix to look like

[1,     2,     3;     
 4,     5,     6;    
 7,     8,     9]

for the case that a=1 and b=1, but I want to be able to change a and b to any numbers if I chose to do so.

Right now I have the matrix

[2,     3,     4;
 3,     4 ,    5;
 4,     5 ,    6]

as you can see the rows are adding by 1 but the columns are not continuing the counting, they add 1 to the number above it. I need help to figure out so that it continues the counting not whatever its doing now.

David Goodmanson 2018-9-6

Does this have to be done with 'for' loops, or is any technique in Matlab all right to use?

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Answer 1

Dennis 2018-9-6

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I hope i got the question right (some possible solutions with increasing number of loops):

   %no loop
    a=1;
    b=1;
    X=ones(1,9)*a;
    Y=ones(1,8)*b;
    Y=cumsum(Y);
    X(2:end)=X(2:end)+Y;
    X=reshape(X,[],3)';
%1 loop
a=1;
b=1;
X=ones(1,9)*a;
for i=1:numel(X)
    X(i)=X(i)+(i-1)*b;
end
X=reshape(X,[],3)';
%2 loops
a=1;
b=1;
X=ones(3,3)*a;
for i=1:3
    for k=1:3
        X(i,k)=a+(i*k-1)*b;
    end
end

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Answer 2