Having trouble importing the lazy_laurent_series module

asked 2019-11-05 00:56:54 +0100

tzeentch
143 ●2 ●8 ●16

updated 2019-11-05 00:57:21 +0100

I am trying to import and use lazy Laurent series rings in sage, documented here: (http://doc.sagemath.org/html/en/refer...). I have the latest version of sage installed, and yet when I attempt to import/install the package it is nowhere to be found.

 from sage.rings.lazy_laurent_series_ring import LazyLaurentSeriesRing
    ---------------------------------------------------------------------------
    ImportError                               Traceback (most recent call last)
    <ipython-input-1-db0f55e1138b> in <module>()
    ----> 1 from sage.rings.lazy_laurent_series_ring import LazyLaurentSeriesRing

    ImportError: No module named lazy_laurent_series_ring

I then tried to download it, perhaps I am not downloading the correct package? Where is it hiding?

sage -i lazy_laurent_series
Error: package 'lazy_laurent_series' not found
Note: if it is an old-style package, use -p instead of -i to install it

answered 2019-11-05 08:51:46 +0100

Emmanuel Charpentier
7744 ●6 ●50 ●153

updated 2019-11-05 08:52:45 +0100

WorksForMe(TM). On a Python 3-based 9.0.beta3 :

sage: from sage.rings.laurent_series_ring import *
sage: L.<z> = LazyLaurentSeriesRing(QQ)
sage: L.category()
Category of magmas and additive magmas
sage: 1/(1 - z)
1 + z + z^2 + z^3 + z^4 + z^5 + z^6 + ...
sage: 1/(1 - z) == 1/(1 - z)

NOTE : from the doc:

The definition of Laurent series rings is not initially imported into the global namespace. You need to import it explicitly to use it.

HTH,

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Comments

It's unfortunately still not working, even after importing the package you mention. I'm running SageMath version 8.1.

sage: from sage.rings.laurent_series_ring import *
sage: L.<z> = LazyLaurentSeriesRing(QQ);
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-9-6587116685f3> in <module>()
----> 1 L = LazyLaurentSeriesRing(QQ, names=('z',)); (z,) = L._first_ngens(1);

NameError: name 'LazyLaurentSeriesRing' is not defined

tzeentch ( 2019-11-06 17:06:40 +0100 )edit

Your Sage is too old (8.1 is quite old by today's standards...). From the doc:

AUTHORS: Kwankyu Lee (2019-02-24): initial version

Emmanuel Charpentier ( 2019-11-06 19:37:42 +0100 )edit

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