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## Re: generating sparse matricies

**From**: |
avraham |

**Subject**: |
Re: generating sparse matricies |

**Date**: |
Sat, 1 Oct 2005 14:11:57 +0200 |

**User-agent**: |
Mutt/1.5.5.1+cvs20040105i |

On Fri, Sep 30, 2005 at 11:07:31PM -0700, Paul Roberts wrote:
>* Hello,*
>* *
>* I am using Octave 2.1.64. I would like to iteratively build a sparse matrix*
>* uring code like:*
>* *
>* X = sparse(10000,1000);*
>* for j=1:1000*
>* X(:, j) = rand(10000,1) < 0.01;*
>* end*
>* *
>* I have found however that when I try X(:,j) = rand(10000,1) < 0.01;, the*
>* matrix X is converted to a full matrix. This happens even if I write: X(:,j)*
>* = sparse(rand(10000,1) < 0.01);*
>* *
>* My questions are: (1) Will this be changed in future versions of Octave and*
>* (2) is there an efficient work around for this issue? I have tried using*
>* sphcat, but that seems to be very slow.*
>* *
>* Thanks!*
>* *
>* Paul*
Hello,
I still have 2.1.64. Asking:
help sprand
I get:
sprand is the user-defined function from the file
/usr/share/octave/2.1.64/site/m/octave-forge/sparse/sprand.m
Which means that you need octave-forge as well.
Good luck, Avraham
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