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##### Activity
• 02:37
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oscarbenjamin on master

Bugfix in minimal_polynomial()… Give AlgebraicNumber a to_ro… Improve AlgebraicNumber.to_roo… and 10 more (compare)

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github-actions[bot] commented #22505
Francesco
@cescofran_gitlab
Sum(x**2, (x, 1, k)).evalf() and expression which derivative is not a constant raise TypeError
this should come from the euler_maclaurin when it compare a symbolic expression to a float...
why the code does not take in consideration the symbolic case?
Janmay Bhatt
@JANMAY007
Hi everyone, I am Janmay from Nirma University, India and I want to contribute into sympy library. I am CSE student, second year. I have done a research in mathematics related to prime numbers which is prime conjecture(here https://www.ijmttjournal.org/archive/ijmtt-v60p505).
This research have function for series of prime numbers and you can generate the any prime with a reference. I have read about the contribution in sympy so may someone please guide me about gsoc
This will make the prime generation faster and precise, which I want to contribute into sympy as well as for issue #19118 in sympy repository
Ayush Bisht
@ayushbisht2001

I found some unusual behaviour in randprime and I try to fix it.

from sympy import randprime
print(randprime(-2,0))
ValueError: no preceding primes

Can someone please review this PR : #20949

laolux
@laolux:wolkendienst.dynv6.net
[m]
@ayushbisht2001 Wouldn't it make sense to go all the way to 2?
for example
print(randprime(0,2)) should also print "no primes exist in the specified range"
Ayush Bisht
@ayushbisht2001
@laolux:wolkendienst.dynv6.net , Now , Is it good to go ?? #20949 .
Aaron Stiff
@AaronStiff
How would I analyze a sympy object to see whether it matches a certain structure? For instance, I want to see if an object/expression matches the structure I*im(z), where z is some complex symbol.
Aaron Meurer
@asmeurer
You can use Wild and match
Aaron Stiff
@AaronStiff
Thanks.
Vishesh Mangla
@Teut2711
class Data:
def __init__(self, string,symbol, value):
self.string = string
self.symbol = sm.Symbol(symbol)
self.value = value

return self.value + other.value if isinstance(other, Data) else other

def __str__(self):
return self.string
def _repr_latex_(self):
return display(Latex(' '.join([self.string, f'({self.symbol})' ,r'\equals', self.value] )))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
c:\users\dell\onedrive\desktop\courses sem8\venv\lib\site-packages\IPython\core\formatters.py in __call__(self, obj)
343             method = get_real_method(obj, self.print_method)
344             if method is not None:
--> 345                 return method()
346             return None
347         else:

<ipython-input-49-83e3f780e89d> in _repr_latex_(self)
11         return self.string
12     def _repr_latex_(self):
---> 13         return display(Latex(' '.join([self.string, f'({self.symbol})' ,r'\equals', self.value] )))
14 # area_each_plate = Data("Area of each plate", 15.8*15.8*SI.cm**2)
15 # inlet_pressure = Data("Area of each plate", 15.8*15.8*SI.cm**2)

TypeError: sequence item 3: expected str instance, Quantity found
how to get the latex out of sympy's Symbol?
neither does f'({latex(self.symbol)})' work
Aaron Meurer
@asmeurer
"TypeError: sequence item 3: expected str instance, Quantity found"
"item 3" is the item at index 3, which is self.value. join requires that every item is converted to a string, so use latex(self.value).
Also I'm not sure, but I think _repr_latex should return a string, not call display().
Ayush Bisht
@ayushbisht2001

With this command python3 -m doctest -v frame.py , I found these error , can anyone help me , why they are failing??

Sidharth Mundhra
@0sidharth
@ayushbisht2001 It looks like you do not have the development version setup properly. I think it is something like you are using sympy 1.7.1 version to run sympy 1.8-dev files
Ayush Bisht
@ayushbisht2001
@0sidharth , how can I update sympy 1.7.1 ?
because, It's not updating further from 1.7.1
! pip install sympy --upgrade
Sidharth Mundhra
@0sidharth
I think you have to go into sympy directory and do pip install -e . in the virtual environment
Ayush Bisht
@ayushbisht2001
Thanks @0sidharth , Now it's working fine ..
Is there some way to return two equations in the same Piecewise condition, like Piecewise(((a, b), Eq(n, 0)), (nan, True)), though writing as Tuple doesn't work? Thanks.
laolux
@laolux:wolkendienst.dynv6.net
[m]
Minor point I just noticed: I don't think you need to check if a<=2, because it is checked already that a<b. But I think this detail also depends on sympy style guides, so somebody else should comment on that
Benoit Martin
@metabsd
Hi, How can I evaluate this in sympy ?
almighty123789
@almighty123789
@metabsd
b1, b2 = symbols('b1 b2')
f = (5b1 - 3b2)**2
@metabsd
f.expand()
stuzenz
@stuzenz

Hi, I am using sympy to help my daughter go through some IGCSE math (while exposing her to some coding) and I am trying to understand, is there a way to have the below expression displayed versus simplified/calculated out.

2**5

Craig Russell
@ctr26
sympify ("2**5", evaluate=False)
Pow(2,5, evaluate=False) also works
stuzenz
@stuzenz
Excellent - thank you. I had tried a few different things - just not the right combination.
Love the sympy library by the way - I am getting more familiar for the library - this group has some useful information which I have also been reading.
stuzenz
@stuzenz

sympify ("2**5", evaluate=False)

Interesting, simplify("2**5",evaluate=False) didn't work for me, but the Pow function did work with evaluate set to False.

Craig Russell
@ctr26
Sympify vs simplify
stuzenz
@stuzenz
Thanks Craig - that did work
almighty123789
@almighty123789
while running some tests, my code is getting some infinte recursion errors, is there a way t o exactly find which statement/test leads to the infinte recursion error?
Sidharth Mundhra
@0sidharth
The tests generally print the traceback, from where you can see the recurring statements
@root-11

Hi - I'm learning and am looking for a hint for setting up an equation.
The problem is naturally expressed as:

# maximize:
#   z = 100*x_1 + 60*x_2 + 70*x_3 + 15*x_4 + 15*x_5

# subject to limits:
#   52*x_1 + 23*x_2 + 35*x_3 + 15*x_4 + 7*x_5 <= 60
#      X_1                                    in {0,1}
#               x_2                           in {0,1}
#                        x_3                  in {0,1}
#                                 x_4         in {0,1}
#                                         x_5 in {0,1}

But I can't find a way to express "x_1 in the set containing {0,1}

It's a knapsack problem.

My personal preference is to use the matrix representation

m = Matrix((
[52,23,35,15,7,-60],
[1,0,0,0,0,0],
[0,1,0,0,0,0],
[0,0,1,0,0,0],
[0,0,0,1,0,0],
[0,0,0,0,1,0]

))

...but I'm not sure how to package the variables for the nonlinsolve function.

@root-11
Sorry if this is a dumb question. I'm just overwhelmed by the amount of documentation.
@root-11
Whilst reading on I'm drifting towards the conclusion that sympy isn't hot on Linear Programming / Simplex method type problems on its own.
@root-11
Ok. Nobody is burning my statements. PuLP seems to be what I need.
Sayandip Halder
@sayandip18
>>> solveset(tan(x), x)
Union(ImageSet(Lambda(_n, 2*_n*pi + pi), Integers), ImageSet(Lambda(_n, 2*_n*pi), Integers))
Shouldn't the answer be simply ImageSet(Lambda(_n, _n*pi))?
Sayandip Halder
@sayandip18

Also,

>>> solveset(sin(cos(x)), x)
ConditionSet(x, Eq(sin(cos(x)), 0), Complexes)

The answer should be something like ImageSet(Lambda(_n, 2*(n-1)*pi))`

I guess this is an issue of improving solveset
Aaron Meurer
@asmeurer
@root-11 yeah, SymPy currently doesn't have algorithms to solve that sort of problem. Anyway, if you are looking for a numerical solution rather than an exact analytic one, then SymPy is generally not your best choice.