Toppling the numeric tower

Gareth McCaughan Gareth.McCaughan at pobox.com
Thu Jul 26 22:54:33 CEST 2001


Guido van Rossum wrote:

> David Eppstein <eppstein at ics.uci.edu> writes:
> 
> > (2) should isintegral() return true for algebraic integers that are not 
> > rational integers?
> 
> Sorry, you lost me there.  What are these?

The square root of 2, for instance. An algebraic integer
is any root of a polynomial equation with integer coefficients
and leading coefficient 1 (e.g., x^2-2). Fact: An algebraic
integer that is rational is in fact an "ordinary" integer;
hence, "rational integer".

Note (not that it matters much here in c.l.py) that some
things are algebraic integers even though they might not
"look" very integral; for instance, (1+sqrt(5))/2.

-- 
Gareth McCaughan  Gareth.McCaughan at pobox.com
.sig under construc



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