id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
14878 Doctest fix for: very slow taylor expansion for composite functions chapoton burcin "Pynac-0.7.0 uses Flint to get univariate series expansions. For comparison,
{{{
now previously
sin(x*sin(x*sin(x*sin(x)))).series(x,8) 50-55µs 13.7s
sin(x*sin(x*sin(x*sin(x)))).series(x,12) 69µs >1min
sin(x*exp(x)).series(x,100) 3.7ms 11.3s
sin(x*exp(x)).series(x,500) 215ms n/a
(sin(x+x^2)*cos(x+x^2)).series(x,1000) 2.86s n/a
}}}
Extensive tests are added with #21730 under `tests/`. Pre-Pynac 0.7.0 the tests need 11s vs 0.2s with pynac-0.7.0.
Previous ticket description:
The following
{{{
f=sin(x*sin(x*sin(x*sin(x))))
f.series(x,8)
}}}
takes something like 30s, which seems a bit too much. Maybe there is some bottleneck somewhere ?
On the other hand,
{{{
f.taylor(x,0,8)
}}}
is faster, but not lightning fast.
In the same spirit, one could try
{{{
sage: x=PowerSeriesRing(QQ,'x').gen()
sage: sin(x)
Traceback (most recent call last):
...
TypeError: cannot coerce arguments: no canonical coercion from Power Series Ring in x over Rational Field to Symbolic Ring
}}}
It would be good if one could apply symbolic functions to power series and get power series when possible.
" defect closed major sage-7.5 symbolics fixed taylor expansion, symbolic function Ralf Stephan Frédéric Chapoton N/A ebaf2c4e031c16b836004f47fbbf62c624016bf6 ebaf2c4e031c16b836004f47fbbf62c624016bf6 #21827