### Re: [sage-devel] Re: SIGSEGV in Maxima

Le vendredi 11 août 2017 11:22:24 UTC+2, Eric Gourgoulhon a écrit : > > Hi, > > Le vendredi 11 août 2017 08:12:42 UTC+2, David Roe a écrit : >> >> Note that this is changed in https://trac.sagemath.org/ticket/23592 >> > > This is not the same part of manifolds code: #23592 >

### [sage-devel] Re: SIGSEGV in Maxima

On Sunday, August 13, 2017 at 12:56:44 PM UTC-7, Emmanuel Charpentier wrote: > > The difficulty is general, and bound to a very simple fact : when z is > complex (iL e. not known to be real), z^(1/3) denotes *some* quantity whose > cube is z, with no way to specify which. This ambiguity is

### [sage-devel] Re: SIGSEGV in Maxima

The difficulty is general, and bound to a very simple fact : when z is complex (iL e. not known to be real), z^(1/3) denotes *some* quantity whose cube is z, with no way to specify which. This ambiguity is lifted when z is known real, where one can specify that, by *convention*, z^(1/3) (or

### [sage-devel] Re: SIGSEGV in Maxima

On 2017-08-12, rjf wrote: > seems to me that asking for the "sign" of b^(1/3) in the complex domain > is nonsense. After thinking about this some more, I think maybe you're right -- SIGNDIFF-SPECIAL, which is doing the c^3 - b*c --> c - (b*c)^(1/3) that leads into trouble,

### [sage-devel] Re: SIGSEGV in Maxima

On Saturday, August 12, 2017 at 4:50:28 PM UTC-7, rjf wrote: > > seems to me that asking for the "sign" of b^(1/3) in the complex domain > is nonsense. There are 3 cube roots. Let q be one of them; it doesn't > matter which. > then - (1+sqrt(3)*i)*q/2are the other two. Yes, two. because

### [sage-devel] Re: SIGSEGV in Maxima

On 2017-08-12, rjf wrote: > seems to me that asking for the "sign" of b^(1/3) in the complex domain > is nonsense. sign(c - (b*c)^(1/3)) actually was encountered when Maxima was trying to find the sign of some other expression. When domain = complex, SIGNDIFF-SPECIAL

### [sage-devel] Re: SIGSEGV in Maxima

seems to me that asking for the "sign" of b^(1/3) in the complex domain is nonsense. There are 3 cube roots. Let q be one of them; it doesn't matter which. then - (1+sqrt(3)*i)*q/2are the other two. Yes, two. because there are two sqrt(3). If you cannot deal with all 3 of them in Sage,

### [sage-devel] Re: SIGSEGV in Maxima

On 2017-08-11, Richard_L wrote: > That's a bit puzzling. In the Sage code, line 36 defines the manifold over > the real field. That is supposed to be inherited by the chart in line 39: > > M = Manifold(1*3,'R^3',field='real',start_index=1) > U = M.open_subset('U') > >

### [sage-devel] Re: SIGSEGV in Maxima

Clearly Robert has found a bug in maxima. Here's a little test further to my earlier "puzzle": If I write in sage as follows: #\$is (equal(-(_SAGE_VAR_r13^2*_SAGE_VAR_r23-_SAGE_VAR_r23^3)/((-_SAGE_VAR_r23^4)+2*_SAGE_VAR_r13^2*_SAGE_VAR_r23^2-_SAGE_VAR_r13^4+_SAGE_VAR_r12^4),0))\$ var('r12 r13

### Re: [sage-devel] Re: SIGSEGV in Maxima

Le vendredi 11 août 2017 15:30:08 UTC+2, Richard_L a écrit : > > Eric, > I will be happy to test as soon as source code is modified. Just let me > know. > For sure I will. Thanks. Eric. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To

### [sage-devel] Re: SIGSEGV in Maxima

Le vendredi 11 août 2017 16:21:45 UTC+2, Richard_L a écrit : > > That's a bit puzzling. In the Sage code, line 36 defines the manifold over > the real field. That is supposed to be inherited by the chart in line 39: > > M = Manifold(1*3,'R^3',field='real',start_index=1) > U = M.open_subset('U') >

### [sage-devel] Re: SIGSEGV in Maxima

That's a bit puzzling. In the Sage code, line 36 defines the manifold over the real field. That is supposed to be inherited by the chart in line 39: M = Manifold(1*3,'R^3',field='real',start_index=1) U = M.open_subset('U') Rho. = U.chart("r12:(0,+oo) r13:(0,+oo) r23:(0,+oo)") One

### Re: [sage-devel] Re: SIGSEGV in Maxima

Eric, I will be happy to test as soon as source code is modified. Just let me know. - Richard On Friday, August 11, 2017 at 2:22:24 AM UTC-7, Eric Gourgoulhon wrote: > > Hi, > > Le vendredi 11 août 2017 08:12:42 UTC+2, David Roe a écrit : >> >> Note that this is changed in

### Re: [sage-devel] Re: SIGSEGV in Maxima

Hi, Le vendredi 11 août 2017 08:12:42 UTC+2, David Roe a écrit : > > Note that this is changed in https://trac.sagemath.org/ticket/23592 > This is not the same part of manifolds code: #23592 deals with comparison of points

### Re: [sage-devel] Re: SIGSEGV in Maxima

Note that this is changed in https://trac.sagemath.org/ticket/23592 David On Fri, Aug 11, 2017 at 2:00 AM, Ralf Stephan wrote: > No, from testing it appears equality proofs are needed by 10 doctests > in src/sage/manifolds/differentiable/metric.py > so my idea does not work.

### [sage-devel] Re: SIGSEGV in Maxima

No, from testing it appears equality proofs are needed by 10 doctests in src/sage/manifolds/differentiable/metric.py so my idea does not work. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving

### [sage-devel] Re: SIGSEGV in Maxima

I think another problem here is that Maxima is called at all. It happens because the manifolds code naively compares two symbolic expressions via '='. This invokes the full equality proof machinery, which is probably not intended:

### [sage-devel] Re: SIGSEGV in Maxima

On 2017-08-10, Richard_L wrote: > The following string sent to maxima causes a seg-fault and core dump: > '#\$is > (equal(-(_SAGE_VAR_r13^2*_SAGE_VAR_r23-_SAGE_VAR_r23^3)/((-_SAGE_VAR_r23^4)+2*_SAGE_VAR_r13^2*_SAGE_VAR_r23^2-_SAGE_VAR_r13^4+_SAGE_VAR_r12^4),0))\$' >