Strange behaviour of "expand" in CAS view (Xcas problem?)

[Nigel (UK)]

(10-16-2014 08:06 PM)parisse Wrote:  I can't reproduce on Xcas
0>> expand(x*2.9e-13+6.3e-13)
2.9e-13*x+6.3e-13
The latest stable version is 1.1.2-10 (version() on windows and mac, dpkg -l giac on linux to check your version).

Sorry about the delay in my reply - real life intervened!

I have re-installed Xcas - version() now returns

Code:

"giac 1.1.2-10, (c) B. Parisse and R. De Graeve, Institut Fourier, Universite de Grenoble I"

My config settings are

Code:

exact real DEG 10 xcas

and epsilon is 10^(-10).

I still have the error described above.

It may be to do with the way in which Xcas treats small numbers, as Han suggests. However in this case Xcas isn't replacing one small number by zero; rather, it is replacing one small number by the other small number in the problem. This is unexpected.