CODEWITHSUNDEEP
matlabmatrixrows
user1968419
user1968419

Reputation: 17

edit rows in a matrix, MatLab

I have a matrix A and I want to multiply every row by 2 using a for loop. 

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

So essentially matlab should output: 

[2  4  6; 
 8  10 12; 
 14 16 18];

I tried:

A = [1 2 3 ; 4 5 6  ; 7 8 9];
for i=1:3
    x= A([i],:)*2;
end

but x outputs as [14 16 18].

How can I get my desired output?

Upvotes: 0

Views: 2499

Answers (3)

Dharini Chandrasekaran
Dharini Chandrasekaran

Reputation: 203

For loops are very very inefficient in MAtlab. I would suggest you learn to work around it when using matlab. For something small like this you may not see any detrimental effect, but for anything large scale, it's a no.

Anyway, for your problem, you can just do x = A*2. That should give you your solution.

Upvotes: -1

Pallavi
Pallavi

Reputation: 1

In think your answers are getting overwritten every time you go in the for loop. You may be able to do something like this:

 for i=1:3
     x([i],:) = A([i],:)*2;
 end

Upvotes: 0

bla
bla

Reputation: 26069

With a for loop that will be:

for n=1:size(A,1)
    x(n,:)=2*A(n,:);
end

But it is much easier to get the same result without a for loop:

x=2*A;

Upvotes: 2

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