Asked by Light
on 6 Jun 2013

Hello my matrix problem?? I tried it in week. But no success!

Here is the matrix

A=[-1,-1,0,0,0;0,0,0,-1,0;0,1,-1,0,-1;0,0,1,0,0;1,0,0,1,1]

Every column has only one 1, one -1 and i have to add them with whole row. Then that column will be 0. It is the first step.. Result must be like that A matrix must be changed A=[-1,-1,0,0,0;0,0,0,-1,0;0,1,0,0,-1;0,0,0,0,0;1,0,0,1,1] 4th row added to the 3rd row. and 4th elements changed 0

Then that operation will be continued until all row changed 0. I think if i write iterate Code, it will be more easier. But failed, some help!

I couldn't write a CODE. How can i write CODE. Please tell me a CODE or structure...

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Answer by Iain
on 6 Jun 2013

Edited by Iain
on 6 Jun 2013

I think you are asking how to make your entire matrix zero, by adding columns of data that already exist.

while any(A) & ~some error for i = 1:size(A,2) % each column col = A(:,i); [plus indp] = max(col); [nega indn] = min(col); if ~(nega => 0 || plus =< 0 ) A(row_no,:) = A(indp,:) - A(indn,:)*plus/nega; end end some error = some check for infinite loops etc. end

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Iain
on 6 Jun 2013

>=, and <= instead of => and =<, I always get them mixed up.

Light
on 6 Jun 2013

A=[-1,-1,0,0,0;0,0,0,-1,0;0,1,-1,0,-1;0,0,1,0,0;1,0,0,1,1];

while any(A) & ~ some error

for i = 1:size(A,2) % each column col = A(:,i); [plus indp] = max(col); [nega indn] = min(col); if ~(nega >= 0 || plus <= 0 ) A(row_no,:) = A(indp,:) - A(indn,:)*plus/nega; end end some error = some check for infinite loops etc. end

Undefined function or variable 'some'.

:-(

Iain
on 6 Jun 2013

"some error" is psuedocode - you should use it to prevent infinite loops, or any other errors that might arise.

If your sole aim is to set that matrix equal to zero by the simplest means possible, you can simply:

A(:) = 0;

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## 1 Comment

## David Sanchez (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/78170#comment_153201

your explanation is not clear, could you please rewrite your question in a way it be clearer?