trac #16149 proposal
trac #16149 proposal
trac #16149 typos
override IPythons show_usage
add hint about debugging
trac #17xxx no loops in vertex_graph of polyhedra
Trac #16149: sage-env exports empty CXXFLAGS

That happens if `CFLAGS` are empty (or not exported at all, which
presumably is the most frequent case) and `CXXFLAGS` aren't either:

{{{
#!sh
if [ "$CXXFLAGS" = "" ]; then
    export CXXFLAGS="$CFLAGS"
fi
}}}

Unintentionally having exported but empty `CXXFLAGS` breaks '''at
least''' MPIR, because it assumes the user had intentionally set them,
so leaves them as they are (empty that is), not passing potentially
important architecture and ABI flags to the C++ compiler (e.g. `-m...`
flags to `g++`).

The solution is of course simple:  Don't (set and) export `CXXFLAGS` if
`CFLAGS` aren't exported either.  Not sure if setting `CXXFLAGS` to
`CFLAGS` in case the latter are non-empty (or empty but exported) is
desirable at all.

URL: http://trac.sagemath.org/16149
Reported by: leif
Ticket author(s): Frédéric Chapoton
Reviewer(s): Volker Braun
Trac #9015: typing `?` on the command line brings up IPython help

I was looking over the shoulder of a new user as he started Sage for the
first time and typed `?` on the command line. This shows the IPython
help text which doesn't mention Sage at all.

We should change this to show the text displayed with `help()`.

Printing some more information when someone types `help` without the
parenthesis would also be nice.

{{{
sage: help
<function help at 0x1d6fc80>
}}}

URL: http://trac.sagemath.org/9015
Reported by: burcin
Ticket author(s): Volker Braun
Reviewer(s): John Palmieri
Trac #17431: no loops in edge-vertex graphs of polyhedra

So far, the vertex_graph method of polyhedra returns looped graphs.

This seems to be a strange thing to do.

Let us change that to graphs with no loops.

URL: http://trac.sagemath.org/17431
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): Nathann Cohen