#8862: failing resolution of a nonlinear system by solve
-------------------------+--------------------------------------------------
Reporter: casamayou | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-4.4.1
Component: calculus | Keywords: solve
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------+--------------------------------------------------
Comment(by zimmerma):
the issue here is not only that Sage returns undefined points (which
indeed duplicates #2617) but
that it fails to find the following (trivial) solutions, which is a
defect:
{{{
sage: sys=[diff(f(x,y), x), diff(f(x,y), y)]
sage: map(lambda s: s.subs(x=0,y=1),sys)
[0, 0]
sage: map(lambda s: s.subs(x=0,y=-1),sys)
[0, 0]
sage: map(lambda s: s.subs(x=1/e,y=0),sys)
[0, 0]
sage: map(lambda s: s.subs(x=-1/e,y=0),sys)
[0, 0]
}}}
For example Maple finds:
{{{
> f := (x,y) -> (x^2 + y^2)^x:
> solve({diff(f(x,y), x), diff(f(x,y), y)}, {x, y}, Explicit=true);
exp(1) exp(1)
{x = 0, y = 1}, {x = 0, y = -1}, {x = - ------, y = 0}, {x = ------, y =
0}
exp(2) exp(2)
}}}
When some solutions are lost, at least a warning should be issued.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8862#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
