Hello,
I have been usage Sage for a few months. Up to now, plotting,
polynomials, and arithmetic functions have been running fine.
Now I'm trying to use the symbolic calculation skills of Sage, but ...
I am getting the error : "unable to simplify to float approximation"
when running, for instance :
var('t')
sin(t)
on a local-hosted jupyter notebook running the Sagemath8.3 kernel. My os
is Ubuntu 18.04
Same error in pure sage :
sage: var('t')
t
sage: sin(t)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-3-17829414d33a> in<module>()
----> 1sin(t)
/xxxxxxxxxxxxxxxxxxxxxx/lib/python2.7/site-packages/sage/symbolic/expression.pyx insage.symbolic.expression.Expression.__float__
(build/cythonized/sage/symbolic/expression.cpp:11836)()
*1426* raise
*1427* except TypeError:
-> 1428raise TypeError("unable to simplify to float approximation")
*1429* return ret
*1430*
TypeError: unable to simplify to float approximation
sage:
On 22/04/2019 21:23, John H Palmieri wrote:
On Monday, April 22, 2019 at 11:03:48 AM UTC-7, slelievre wrote:
Having defined
sage: x = SR.var('x', 20)
sage: a = [x[11], x[8], x[10], x[9]]
sorting by repr or by str is disappointing:
sage: sorted(a, key=repr)
[x10, x11, x8, x9]
sage: sorted(a, key=str)
[x10, x11, x8, x9]
As Dima suggests, one can
./sage --pip install natsort
and then
sage: from natsort import natsorted
sage: natsorted(a)
[x8, x9, x10, x11]
Without any pip install, one can alternatively use `LooseVersion`:
sage: from distutils.version import LooseVersion
sage: sorted(a, key=lambda z: LooseVersion(str(z)))
[x8, x9, x10, x11]
Note: "./sage --pip install" requires Python's OpenSSL module to
be built.
If it was not built, install OpenSSL,
Alternatively, you should be able to download a tar.gz file from
https://pypi.org/project/natsort/#files, and then do
./sage --pip install /path/to/natsort-6.0.0.tar.gz
- either system-wide with a package manager, for example
under Debian or Ubuntu do
sudo apt-get install openssl libssl-dev
- or just for your Sage installation by running in a terminal
from the Sage root directory:
sage -i openssl
sage -i pyopenssl
Once OpenSSL is installed by one of the above methods,
Sage's Python needs to be rebuilt by running the following
in a terminal from the Sage root directory
sage -f python2 && sage -f python3 && make
Note also, if x and a were defined as above:
sage: x = SR.var('x', 20)
sage: a = [x[11], x[8], x[10], x[9]]
then without any pip install or any import, one could also do:
sage: sorted(a, key=lambda z: x.index(z))
[x8, x9, x10, x11]
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