Re: late Re: A Simple Matrix Construction Question

[John W. Eaton]

On  5-Feb-2003, David Bateman <address@hidden> wrote:

| If this is what you want to do, why not do for example
| 
| m = 4;
| n = 5;
| y = rand(1,n);
| x = y(ones(m,1),:);
| 
| where x will now be a m by n matrix with m copies of y,
| one per row. Indexing should definitively be more
| computationally efficient than doing a matrix multiply
| which is O(n^3).

Indexing is not necessarily more efficient.  See

  http://www.octave.org/mailing-lists/help-octave/2003/133

jwe



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