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## Re: Some Octave newbie questions regarding number format and matrices

**From**: |
Jordi Gutiérrez Hermos |

**Subject**: |
Re: Some Octave newbie questions regarding number format and matrices |

**Date**: |
Sun, 20 Sep 2009 01:06:58 -0500 |

2009/9/19 hdfrango <address@hidden>:
>* 1. is there any way to force octave to express numbers in fraction form, to*
>* avoid loss of precision?*
If you don't want to lose precision, you need a symbolic CAS, like
Sage or Maxima, not Octave. Octave is optimised for speed with
hardware floats, and although it does have a symbolic addon in the
Octave-Forge packages, this is more of an afterthought than core
functionality. In particular, it only allows you to change the
precision. I don't believe a bignum interface exists for Octave.
>* 2. when I want to computer the inverse of a matrix, I have to do inv(A'),*
>* computing the inverse of the transpose, in order to get the correct answer.*
>* Why is that?*
My guess is that you've either found a bizarre bug in Octave, or you
are confused about what the inverse of a matrix should be. Can you
show us a specific matrix for which inv(A) produces the transpose of
the correct inverse?
- Jordi G. H.