Re: [julia-users] Efficient way to iteratively grow a matrix up to a predefined maximum number of columns and pop/append columns after the maximum is reached

[Tim Holy]

Do you actually care about the order of columns? Or can you just use a cyclic 
representation?

V[:, mod1(col, N)] = v

--Tim

On Sunday, May 11, 2014 04:48:08 PM Carlos Baptista wrote:
> I have an iterative algorithm in which two matrices with a fixed number of
> rows grow in number of columns. The algorithm requires only the last
> *N*columns (where N is a predefined fixed integer). If the number of
> columns grow to *N + d*, then the first *d* columns are no longer required
> and can be deleted/overwritten. So what would be an efficient way to let a
> matrix grow up to *N* columns and to continue by popping the first column
> before appending a new one? Please keep in mind that I need to perform
> matvec and qr-decompositions on these matrices.
> 
> A pseudo code of what I would like to do in an efficient manner is this:
> 
> v = myFuncV()
> w = myFuncW()
> 
> if size(V, 2) == N
>     V = [V[:, 2:N] v]
>     W = [W[:, 2:N] w]
> else
>     V = [V v]
>     W = [W w]
> end