How to implement the output matrix without if conditions

Hi.

This is a review problem that requires the use of nested loops to output the following matrix.

1

2 3

3 4 5

4 5 6 7

5 6 7 8 9

Here is my code, i use the complex if statement to output.

matrix = []; % create empty matrx

nums = 0; % set a variable named nums and euqal to zero

nums_three = 3;

nums_four = 4;

nums_five = 5;

% use nested loop

for i = 1:5

for j = 1:i % the nums of columns will increase with the end of one outer loop

nums = nums + 1;

matrix(i,j) = nums;

if (i == 3)

matrix(i,j) = nums_three;

nums_three = nums_three+1;

elseif (i == 4)

matrix(i,j) = nums_four;

nums_four = nums_four+1;

elseif(i == 5)

matrix(i,j) = nums_five;

nums_five = nums_five + 1;

end

end

end

disp(matrix);

Here is my output

1 0 0 0 0

2 3 0 0 0

3 4 5 0 0

4 5 6 7 0

5 6 7 8 9

The first question i want to ask is that how can i remove zero in this matrx?

The second question is that Is there another way to output the matrix without using if- statement?

Thank you all.

Answer 1

[KSSV]

n = 5 ;
A = zeros(n) ;
for i = 1:n
    for j = 1:i
        A(i,j) = i+j-1 ;
    end
end
A

You cannot remove zeros, if you want it as a matrix. Other option is you can replace zeros with NaNs.

[Shuoze Xu]

Thank you.

May you tell me what is meaing of iwant, Is it just a variable?

[KSSV]

It is supposed to be A. I have edited the answer.