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Topic: Integrating bsxfun in a for-loop
Replies: 1   Last Post: Feb 23, 2014 5:02 PM

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 Curious Posts: 2,359 Registered: 12/6/04
Re: Integrating bsxfun in a for-loop
Posted: Feb 23, 2014 5:02 PM

"Timothy Liang" <timothy.tliang@gmail.com> wrote in message <leb9qk\$qn0\$1@newscl01ah.mathworks.com>...
> Hi,
>
> I am trying to integrate bsxfun into a loop... but it turned out to be unsuccessful...
>
> i=1:10000
> x=i/10000
> for q=0:20
> X=bsxfun(@power,x',q);
> [Q,R]=qr(X)
> ...
> end
>
> What I want was that as q increase, the matrix would be
> for q=0
> X=x1^0
> x2^0
> x3^0
> ...
>
> then for q=1
> X=x1^0 x1^1
> x2^0 x2^1
> x3^0 x3^1
>
> for q=2
> X=x1^0 x1^1 x1^2
> x2^0 x2^1 x2^2
> x3^0 x3^1 x3^2
> and so on...
>
> However, the result of my codes was Xs are always 10000by1 column matrices, where the first matrix is x^0, second one x^1...
> How do I fix this? Thanks in advance!!!!

You are overwriting X each time thru your for loop.
You need to modify the above code to something like:

i=1:10000
x=i/10000
maxq = 21
X = zeros(maxq,length(x)) % preallocatefor efficiency
for q=1:maxq
X(q,:)=bsxfun(@power,x',(q-1));
[Q,R]=qr(X)
...
end

Date Subject Author
2/22/14 Timothy Liang
2/23/14 Curious