I have problem with while loop.

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Tran Thien
Tran Thien on 17 Nov 2021
Commented: Chunru on 17 Nov 2021
So I have homework about Gaussian Elimination, when input matrix b I want to ensure that the input matrix has the same number of rows as matrix A and it must be in a column matrix so I tried these code with while loop:
A=input('Input matrix A');
b=input('Input matrix b in column form');
szA=size(A)
szb=size(b)
while (szb(1,1)~=szA(1,1) && szb(1,2)~=1)
b=input('Matrix b is not in column form,please re-input');
szb=size(b)
if (szb(1,1)==szA(1,1)&& szb(1,2)==1)
break
end
end
Ab=[A b]
My goal here is when the input matrix b has a different number of rows than that of matrix A and/or the number of columns is not equal to 1 then the user has to re-enter the matrix. When both conditions are met then break the while loop and continue.
But when I tested with matrices like:
A=[1 2;2 1] b=[1 2;2 1]
The while loop still break and give me matrix Ab.
Or
A=[1 2;2 1] b=[1;2;3]
The while loop breaks and the program gives me the horzcat error (I understand that matrix b don't have the same number of rows as matrix A will cause this error)
Please help. Thank you.

Accepted Answer

Chunru
Chunru on 17 Nov 2021
Make the following change:
%while (szb(1,1)~=szA(1,1) && szb(1,2)~=1)
while (szb(1,1)~=szA(1,1) || szb(1,2)~=1)
  2 Comments
Tran Thien
Tran Thien on 17 Nov 2021
It works! Thank you very much.
Chunru
Chunru on 17 Nov 2021
To make your code easer to read, you can chnage szb(1,1) to szb(1) and so on.

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