## Where communities thrive

• Join over 1.5M+ people
• Join over 100K+ communities
• Free without limits
##### Activity
• Sep 12 01:39

• Sep 11 12:19

Implemented leading term and ns… (compare)

• Sep 10 03:21

• Sep 08 06:28

• Sep 08 03:43

Changed the outputs being retur… (compare)

• Sep 07 09:34

Changed leading term being ret… (compare)

• Sep 07 07:27

Removed Redundant block from le… (compare)

• Sep 07 02:44

anutosh491 on GSoC_Pr4.3_Implementing_some_series_method_for_uppergamma_lowergamma_expint_and_other_errors_functions

Implemented some series methods… (compare)

• Sep 06 16:44

Removed Order term (compare)

• Sep 06 11:39

added test cases for limits and… (compare)

• Sep 06 10:51

Implemented leading term and ns… (compare)

• Sep 06 10:40

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

• Sep 06 04:13

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

This commit does the following … Refactored mrv_leadterm in grun… Fixed errors arising for limits… and 3 more (compare)

• Sep 06 02:08

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

fix(integrals): handle degenera… functions: Generalised Dirichle… author: update Megan Ly in .mai… and 23 more (compare)

• Sep 05 14:16

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

Changed if condition for bessel… (compare)

• Sep 05 02:49

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

Improved code quality (compare)

• Sep 03 10:24

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

changed is function to equality… (compare)

• Sep 03 10:14

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

fixed failing tests (compare)

• Sep 01 12:23

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

Fixed code quality (compare)

• Sep 01 12:00

anutosh491 on GSoC_Pr4.1_Implementing_few_series_methods_for_bessel_functions

Added case where number of term… (compare)

I only want the "otherwise" result
Andreas Schuldei
@stockh0lm
hi, are user questions ok here?
Judging from scrollback, they are. :-)

I need to create a vector function in sympy with actual vectors, that can be transformed between coordinate systems.

I saw this https://stackoverflow.com/questions/46993819/how-to-create-a-vector-function-in-sympy which uses Matrix() as a workaround.

I need to transform my input and output vector from one coordinate system to another (and back). How are vector functions done in that case?

def B_el(r_vec):

r1 = r_vec.i

r2 = r_vec.j
u = sin(r1)+cos(r2)
v = -cos(r1)+sin(r2)
return Matrix([u, v, 0])
Andreas Schuldei
@stockh0lm
formatting broken?
ThePauliPrinciple
@ThePauliPrinciple
Depending on what you "vector" is, it will transform differently under a coordinate transform
e.g. a velocity and a coordinate transform completely differently with a non-linear coordinate transformation
And in the case of a velocity, you could have it transform covariantly or contravariantly
Andreas Schuldei
@stockh0lm
the input vector is a radius, so distance and direction. the output vector is a magnetic field vector.
so it is just the geometic transformation. split up the three spatial components differently, maintain the size
part of the task is to identify the coordinate transformation - the rotation angels and location vector. But that comes later, after having figured out how to write a vector function :-)
Andreas Schuldei
@stockh0lm
I still am unclear as to how to return a vector
def B_el(r_vec):

r1 = r_vec.i

r2 = r_vec.j
u = sin(r1)+cos(r2)
v = -cos(r1)+sin(r2)
return Matrix([u, v, 0])
What would i need to change in order to return a vector, which can be transformed into a different (also resting) coordinate system, differing in axis rotations and a location shift?
ellydo17
@ellydo17
Hello, I am a new member to SymPy. I look forward to contributing to SymPy as a developer. Do we have different channels for SymPy users and developers?
Andreas Schuldei
@stockh0lm
Traceback (most recent call last):
File "C:/Users/Andreas Schuldei/PycharmProjects/lissajous-achse/hgü-kabel-detektion-symbolic.py", line 109, in <module>
result = solve(equations, (CM0, theta_i, theta_j, theta_k, i, a, B_earth))
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py", line 1096, in solve
solution = _solve_system(f, symbols, **flags)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py", line 1730, in _solve_system
i, d = _invert(g, *symbols)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\solvers\solvers.py", line 3118, in _invert
rhs -= indep
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py", line 2194, in __sub__
return Rational.__sub__(self, other)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py", line 89, in __sympifyit_wrapper
return func(a, b)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py", line 1725, in __sub__
return Number.__sub__(self, other)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py", line 89, in __sympifyit_wrapper
return func(a, b)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\numbers.py", line 733, in __sub__
return AtomicExpr.__sub__(self, other)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py", line 251, in _func
return func(self, other)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py", line 126, in binary_op_wrapper
return f(self)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\core\decorators.py", line 127, in binary_op_wrapper
return func(self, other)
File "C:\Users\Andreas Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\vector\basisdependent.py", line 352, in __rsub__
raise TypeError("Invalid argument types for subtraction")
TypeError: Invalid argument types for subtraction
How can I inspect the individual equations in the list equations to narrow this down? The equations are relatively long, and I have no clue how to find this.
Sean Logan
@fountain23
Hello, I have discovered a bug with sympy.vector.divergence() when used in cylindrical coordinates
divergence( R rhat) gives 2, the correct answer. But divergence( 1 rhat) gives 0. Wrong! The correct answer is 1/R
N = CoordSys3D('N', transformation='cylindrical', vector_names=("r", "phi", "z"), variable_names=("R", "PHI", "Z"))
R = N.R
rhat = N.r
lesshaste
@lesshaste
The channel isn't as active as it should be. You might be better off with the mailing list
Anutosh Bhat
@anutosh491
Should using subs back and forth make any difference mathematically ? This is for cases having log where I have seen this multiple times
>>> (log(0/a)).subs(a, 0)
zoo
>>> (log(b/a)).subs(a, 0).subs(b, 0)
nan
>>> (log(b/a)).subs(b, 0).subs(a, 0)
zoo
Aman Thakur
@jhonsnow456
#22416 I have made my first PR. I need help regarding that it has not been merged
Infinil
@Infinil
hello.. I am very new to open source development.. I wanted to ask if I can directly start contributing my cloning the repository and then commit the changes or I need to fork it first and then start working on it?
@avats-dev
Can anyone tell me where the code for finding a function's domain or range is implemented? In case it varies for the type of function, I need the one for trigonometric functions.
Anutosh Bhat
@anutosh491
Hello guys , I am working on couple of Pr's extending the functionality of the doit method in the concrete module , I noticed that one inconsistency leads to couple of errors . Product(1, (n, 1, oo)).doit() returns 1 and 1**oo returns NaN. Other integers work as expected . These expressions are equivalent right ??? or am I missing something !
Kalevi Suominen
@jksuom
@anutosh491 The expressions are not equivalent. The infinite product is the limit of finite partial products Product(1, (n, 1, N)) = 1 as N tends to oowhile 1**oo is the limit of f(x)**g(x) as f(x) -> 1 and g(x) -> oo. See the docstring of Pow.
Anutosh Bhat
@anutosh491
Thanks for the help ! Now I realize what information was I ignoring !
Anutosh Bhat
@anutosh491
Hey guys ! I am working on a Pr based on the as_leading_term() method of core/expr.py (specifically on multivariable cases) . I would be glad if someone could clarify whether (1/x + y).as_leading_term(x) and (1/x + y).as_leading_term(y), both should give back 1/x as the ouput !!
miro

:point_up: November 9, 2021 2:19 AM
yes, i believe that 1/x would be the lowest order term of both series expansions (when expanding around x it is the x^-1 term, when expanding around y it is the y^0 term): https://github.com/sympy/sympy/blob/00d6469eafdd4aac346a0b598184c15f2560dbe5/sympy/core/expr.py#L3411-L3445

it's a poorly named function. leading term to me means the part of the polynomial with the highest order, not the lowest order part of a series expansion.

i have a question myself! i have been trying to solve a toy special relativity problem using sympy https://colab.research.google.com/drive/12JptFSkLoyzwjnpFaCaNmA-2jKNsKcCQ .
one question i had is regarding the solver. in my problem, i have vectors $\hat{m} and$\hat{n}\$, parameterized by sympy symbols. when i try to add the constraint that m + n = 0 to the solver, it pretty much never finishes. if i straight up get rid of the symbols for m and define it as m = -n however, the solve finishes quickly and gets the solution as expected
is there anything i am doing wrong in using the sympy solver?
mozhdd
@mozhdd

Hello!
Is there any solution not to evaluate double equals ('==')?
Here is my simplified example:

from sympy.parsing.sympy_parser import parse_expr
expr = parse_expr('a == 1 + a', evaluate=False)

That returns False. It seems to be flag evaluate=False is ignored.
But, operation for ex. '<=' works 'properly' (for me) and returns:

>>> expr
a <= a + 1
>>> expr.func, expr.args
(<class 'sympy.core.relational.LessThan'>, (a, a + 1))

I need operation '==' has '<=' behavior during parsing with flag evaluate=False and return:

 >>> expr.func, expr.args
(<class 'sympy.core.relational.Equality'>, (a, a + 1))

George Bisbas
@georgebisbas

Dear all at Sympy, congrats on your work!
I am trying to use sympy Min/Max to evaluate a set of variables.
I have looked at: https://docs.sympy.org/latest/modules/functions/elementary.html#min
and
https://docs.sympy.org/latest/guides/assumptions.html

e.g.
a, b, c, d (we have no knowledge for them)
sympy.Max(a,b,c,d) = Max(a,b,c,d)

In case I have the hypothesis that a>c can I somehow get
sympy.Min(a,b,c,d) = Min(a,b,d) ?
Any help appreciated,
best,
George

Nicholas Chisholm
@nchisholm

I seem to have found a wrong result when evaluating $\int dx/|x|$.

>>> x = symbols('x', real=True)
>>> integrate(1/abs(x), x)
Piecewise((-log(x), x <= 0), (nan, True))

The expected answer is $sgn(x) \log(|x|)$ except at x=0, where it is undefined (nan). Sympy gives nan for all x>0. Is this a known issue? I couldn't find one on Github. Just checking so I do not open a duplicate bug report.

Anutosh Bhat
@anutosh491
I can see, couple of issues regarding integrate giving wrong output for functions closely related to 1/x . Closely related in the sense that they can be obtained after some modification or transformations on 1/x but even I haven't been able to spot the above issue . Maybe you should report ?? @nchisholm
Shilpi
@shilpiprd
could somebody tell me which open source testing system sympy uses?
Shilpi
@shilpiprd
I recently created a file in sympy/doc/src/tutorial as non_commutative.rst.
I tried running tests on this file in jupyter lab

import sympy
sympy.doctest("Documents/sympy/doc/src/tutorial/non_commutative.rst")

i tried on my forked folder of sympy

it keeps saying True even though my PR #22503 shows one error
Kuldeep Borkar Jr
@KuldeepBorkar

Hello SymPy Community,
My name is Kuldeep Borkar I am pursuing B.tech currently and just started
using sympy a few days ago and now I would love to make contributions
towards SymPy.

Before contributing I just:

--> Visited the SymPy documentation.
--> Completed the tutorial available on it.
--> Forked the repository.
--> Cloned the repository.
--> Read the Contributing Guidelines, Style Guide, CODE_OF_CONDUCT.

Shall I now start making contributions or there's something I shall know before initiating?
and yes if I have some queries will it be okay if I ask here itself?

mostlyaman
@mostlyaman
@shilpiprd The failing test shows traceback
name "symbols" is not defined etc . I think you may need to import the required function you have used before the code in documentation.
ThePauliPrinciple
@ThePauliPrinciple
@KuldeepBorkar https://github.com/sympy/sympy/wiki/Development-workflow was really useful to me
Shilpi
@shilpiprd
@mostlyaman Thanks a lot!
Shilpi
@shilpiprd
however the problem seems to be: bin/doctest --force-colors
mostlyaman
@mostlyaman
@shilpiprd I know bin/doctest is failing. I was talking about the traceback given by the test. Don't worry your recent commit removed the name errors. There just a few more errors to solve for the test to pass. I hope you are also able to look at the tracebook for the test.
Hello everyone. Does anyone know any good resources on learning how to extend SymPy? The existing documentation seems to only cover how to USE SymPy but not how to extend it. I would like to add a custom form of Mul but there seems to be quite a lot of internal checks preform instead of simply calling __mul__. Anyone know where would-be contributors could learn about the internal flow/architecture of SymPy? Thanks.