Re: Some Octave newbie questions regarding number format and matrices

[Jordi Gutiérrez Hermos]

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.