Wow, I must have misunderstood, thanks! I just checked
https://github.com/sagemath/sage/blob/master/src/sage/symbolic/assumptions.py
<https://github.com/sagemath/sage/blob/master/src/sage/symbolic/assumptions.py#L559>
and I find only a few references to Pynac, exclusively in the
documentation string. Acceptable features are all taken from maxima:
`maxima('features')`
So you are saying that the assumptions() are used by both Pynac and
maxima? You're right, there is also
https://github.com/sagemath/sage/blob/master/src/sage/symbolic/expression.pyx#L1786
<https://github.com/sagemath/sage/blob/master/src/sage/symbolic/expression.pyx#L1916>
Since assume() affects both pynac and maxima evaluations, I guess that
taking it out of `var()` is not a good idea. How else could we make
`var(..., domain=...)` faster?
On 06/20/2017 07:05 PM, Ralf Stephan wrote:
The existing bridge to/from Pynac has to include the forget() call, of
course, and your example only shows that it works.
https://github.com/sagemath/sage/blob/master/src/sage/symbolic/expression.pyx#L1916
https://github.com/sagemath/sage/blob/master/src/sage/symbolic/expression.pyx#L1994
https://github.com/sagemath/sage/blob/master/src/sage/symbolic/assumptions.py#L559
https://github.com/pynac/pynac/blob/master/ginac/assume.cpp#L43
On Tue, Jun 20, 2017, 16:04 Stan Schymanski <[email protected]
<mailto:[email protected]>> wrote:
Actually, ex.is_real() queries the assumptions() data base, not
the GiNaC/Pynac info flags. Example:
var('test', domain='real')
print test.is_real()
forget()
print test.is_real()
Returns:
True
False
I think your proposal below would be great. Remove assume() from
variable creation, but get the information from Pynac and convert
to assumptions when calling maxima.
On 06/15/2017 08:17 AM, Ralf Stephan wrote:
The "more persistent domains() database" exists already in part
as GiNaC/Pynac info flags that are set in parallel to Maxima's
assumptions. They can be queried with ex.is_real() etc...What is
not saved in Pynac are less elementary assumptions like x>1,
y+z==pi. Now instead of caching all assumptions in a database
(either Python or C++) and sending to Maxima on demand in bulk,
another possibility could be, as you say, to just remove the
assume calls on variable creation because they are all elementary
assumptions. Then when Maxima needs them for integration, solving
etc take the information from Pynac and do assumes for just those
variables that are needed. Am I missing something?
On Wednesday, June 14, 2017 at 6:14:39 PM UTC+2, Stan wrote:
As mentioned in https://trac.sagemath.org/ticket/23138, the
assume() command takes a lot of time, which is very annoying
when defining a lot of variables using var() including a
domain information. var('x', domain='real') passes the domain
information to ginac and adds it as an assumption to
assumptions(), so that it can be considered by maxima.
However, since assumptions() can both store much more
information than just the domain information, and on the
other hand all the information is lost when someone executes
forget(), I am wondering if this code should not be removed
from src/sage/symbolic/ring.pyx, Lines 1017-1027, in favour
of a more persistent domains() database, which could be
injected into assumptions() by the user if needed. Any
thoughts on this?
Cheers
Stan
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