sympy/sympy

A computer algebra system written in pure Python http://sympy.org/ . To get started to with contributing https://github.com/sympy/sympy/wiki/Introduction-to-contributing

Het Patel

@hetp111

(sorry for these silly questions... I am trying my best ,i just need some guidance )

Malkhan Singh

@Malkhan52

I'm getting this error '''>>> expr = cos(x)

expr.subs(x-1,y)
cos(x)
expr = cos(x+1)
expr.subs(x-1,y)
cos(y + 2)
'''

where will it be in code?

Aaron Meurer

@asmeurer

Somewhere in the core

I guess it's because Add does the smart substitution but Symbol does not

The cosine is irrelevant. It's the same with x.subs(x - 1, y) vs. (x + 1).subs(x - 1, y)

Malkhan Singh

@Malkhan52

yeah that's why i'm searching subs()

Malkhan Singh

@Malkhan52

got that in basic.py

Aaron Meurer

@asmeurer

Subs is implemented on the different classes in _eval_subs

So Symbol._eval_subs should do the same thing as Add._eval_subs.

Adoa Coturnix

@adoa

@asmeurer: I am somewhat confused regarding the simplification. Apparently there is a difference between simplify(a_list) and [simplify(element) for element in a_list]. With the latter, I get the same expressions as in Mathematica, the former does not simplify at all o_O. In any case: thanks for opening the issue :-)

Aaron Meurer

@asmeurer

I don't know why simplify returns a list unchanged. In general, though, you shouldn't rely on SymPy functions automatically vectorizing over lists

Ashwin Shenoy

@Ashwin-Shenoy-NITK

In the ellipse class, do hradius & vradius represent the semi-major axis length & semi-minor axis length respectively ?

It's a bit unclear in the docstring. I take it they are being represented as radius vectors from the origin along the major & minor axis ?

Akshit Srivastava

@akshitt

Hi I am Akshit, fresher in CS at Indian Institute of Technology, Bombay. Could someone guide me to a basic level bug to start with?

I have some basic level knowledge in Python, FLINT, NumPy

Het Patel

@hetp111

@akshit1511 Hi, i am also new, i'll tell you what i'll be doing to get started, first of all i'll learn to use git and github and then https://github.com/sympy/sympy/wiki has a lot of information on how to start

@akshit1511 Tell me if i am missing something.

Akshit Srivastava

@akshitt

@hetp111 try reading this instead http://try.github.io/

Het Patel

@hetp111

@akshit1511 I'll try. Thanks!

Yatna Verma

@yatna

Printing latex(pi) yields to \\pi whereas the correct representation in LaTex should be just \pi , is the extra '\' a bug or requirement?

Sidhant Nagpal

@sidhantnagpal

"\\pi" is correct. \\ is used to escape \.

Yatna Verma

@yatna

okay, thanks

Kalevi Suominen

@jksuom

'\\pi' is the representation of the (internal) Python string created by latex(pi). You can use print(latex(pi)) to see how the output will appear in the LaTeX source.

Divyam Sharma

@divyam102

what level of python is required in order to contribute for sympy?

Björn Dahlgren

@bjodah

I'm trying to hunt down where in my code I'm using a now deprecated sympy function. I'm using pytest & python 3.7 and I'm looking at the python docs. This should work, but I can't seem to make it trigger:

$ PYTHONWARNINGS='ignore,error:::sympy' PYTHON=python3.7 PYTHONPATH=~/vc/sympy ./scripts/run_tests.sh chempy/util/pyutil.py
==== 6 passed, 1 skipped in 0.53 seconds ====
/home/bjorn/vc/sympy/sympy/matrices/matrices.py:2491: SymPyDeprecationWarning: 

Dot product of non row/column vectors has been deprecated since SymPy
1.2. Use * to take matrix products instead. See
https://github.com/sympy/sympy/issues/13815 for more info.

  useinstead="* to take matrix products").warn()

if I change the PYTHONWARNINGS environment variable to simply error::DeprecationWarning it triggers way before actually running the tests:

Traceback (most recent call last):
...
  File "/opt/py37/lib/python3.7/site-packages/_pytest/assertion/rewrite.py", line 6, in <module>
    import imp
  File "/opt/py37/lib/python3.7/imp.py", line 33, in <module>
    DeprecationWarning, stacklevel=2)
DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses

does anyone know the proper syntax to specifically turn SymPy warnings into errors?

(I also tried PYTHONWARNINGS='ignore,error::DeprecationWarning:sympy' and a few other combinations to no avail)

Aaron Meurer

@asmeurer

I think use SymPyDeprecationWarning instead of DeprecationWarning

Björn Dahlgren

@bjodah

Thanks, tried that too, it spits out Invalid -W option ignored: unknown warning category: 'SymPyDeprecationWarning' and tests still pass.

Aaron Meurer

@asmeurer

Really it has to be a known category?

Björn Dahlgren

@bjodah

Looks like it, also tried:
PYTHONWARNINGS='error:::sympy[.*]'
PYTHONWARNINGS='error::DeprecationWarning:sympy[.*]'

Aaron Meurer

@asmeurer

Well warnings.filterwarnings should work. I think we use that in SymPy itself

I guess you'll have to use that and run the tests from within Python.

Ok apparently you have to specify warnings from external modules with a module name, like sympy.SymPyDeprecationWarning

But it looks like it doesn't work because you have to import it from sympy.utilities.exceptions.

And -W"error::sympy.utilities.exceptions.SymPyDeprecationWarning" gives Invalid -W option ignored: invalid module name: 'sympy.utilities.exceptions'

Maybe I'm doing it wrong.

Björn Dahlgren

@bjodah

Don't know, to me it looks right (but this is all new to me, hence me asking here). I'll use filterwarnings (or just edit matrix.py for a sec to throw). Would've been nice if this worked.

Aaron Meurer

@asmeurer

I don't know. Based on the code from https://github.com/python/cpython/blob/3.7/Lib/warnings.py#L239, -W"error::sympy.utilities.exceptions.SymPyDeprecationWarning" should work

Does it work for you?

Björn Dahlgren

@bjodah

No, I can't get it to trigger. Unsure if py.test might have something to do with it though

Aaron Meurer

@asmeurer

You can open an issue about it. I think at the very least we should move SymPyDeprecationWarning into __init__.py.

Björn Dahlgren

@bjodah

submitted #15130

Ashwin Shenoy

@Ashwin-Shenoy-NITK

Hello, everyone ! I was going through the workflow & came across the guidelines for writing commit messages. sympy/sympy@bf0e81e

Is it really necessary to write an example for the commit message ?

I understand the description is important.

Ashwin Shenoy

@Ashwin-Shenoy-NITK

Also, for the evolute of an ellipse, I can't see any test case added. Do the methods returning a sympy expression don't need a test case ?

Ayushman Koul

@ayushmankoul

Hello everyone.My name is Ayushman Koul and I am a 3rd year student studying Computer Engineering at GCET Jammu. I wish to participate in GSOC 2019 through Sympy and contribute to the community as much as I can.@hetp111 From my personal experience I would suggest you to take https://in.udacity.com/course/how-to-use-git-and-github--ud775-india course to have better understanding .

Ayushman Koul

@ayushmankoul

@asmeurer Sir I am interested in working on this project idea Please provide me the guidance how should I proceed further on this project.

Kalevi Suominen

@jksuom

@ayushmankoul It seems to me that the project idea text is outdated. Most of it has already been implemented in the factortools module except what is suggested in the last sentence: "You can go further and extend...". Algorithms for that part may not be easily available in the literature, if at all.

Ayushman Koul

@ayushmankoul

@jksuom Thank You sir for responding.When will be the GSoC ideas page be updated since some projects may have been completed during this year GSoC ?

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