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
Hi, is sympy 1.9 officially released? I saw it is tagged on github, but the usual files for downloading are missing and pypi also only lists 1.9cr1 as latest version. The sympy.org website is also not helpful in this regard, showing the release of 1.7.1 as latest news.
Hi guys , I was solving an issue regarding functions/limits and I came across something which might help . So do we have any method /function in sympy that checks whether some function/expression might encapsulate or bound another expression . Like is there any way I could check something like -1/x < cos(x)/x < 1/x or even one sided
Hi, it seems that the
.subs function is quite slow. When I have a long expression e (can contain nonlinear terms like x**2, y*x*z), calling e.subs(some_dict) takes quite sometime (a sec or so). In fact subs is often slower than solving for large equations. Am I using subs correctly?
hi guys i'm new with sympy, so can anyone help me with solving this problem?
I was trying it on my own, but i can't get a grip on how to solve this Error
import sympy as sp
from sympy import exp, oo
sp.init_printing()
x = sp.Symbol("x")
a, m, h = sp.symbols("a, m, h", positive = True)
A = sp.Symbol("A")
f = exp(-2 * a * m * x**2 / h)
int_f = sp.integrate(f, (x, 0, oo))
eq1 = 2 * (abs(A))**2 * (int_f) - 1
print(sp.solve(eq1, A))
wow it works thank u!!!!
Hello all. Henry here , I'm using sympy for the first time for one of my course project reports at my University. The course is based on series and summations overall and while trying to get familiar I realized that
Sum((-1)**(x+1) + (-1)**(x+2) , (x, 1, oo)).is_convergent() is not returning the expected result and raises a TypeError saying Invalid NaN comparison , is this a meaningful error or Am I missing something useful ?Maybe I could raise an issue ?
Try:
sym.simplify(sym.Sum((-1)**(x+1)+(-1)**(x+2),(x,1,sym.oo)))
So basically try to simplify the expression, may yield some more insight also in other cases.
@Henrysm41987301_twitter hey Thanks for pointing this out . No need to raise an issue ,there is a fix for similar errors in sympy/sympy#22200 which is currently being reviewed by @oscargus and others .Maybe after that is fixed you could use this expression!
1 reply
When we create an undefined function using Function(name), it is possible to add attributes to it using kwargs, e.g. F=Function('F', foo=bar), which will expose F.foo, as well as consider it a different function if foo is not the same. I'm looking for similar behaviour when subclassing Function, is there a way to do so?
It might help if you create the symbol with the same assumptions as whatever you are substituting
it would be great if this was all inside diophantine
Last year expansion was causing slowdowns in the .equals method. In sympy/sympy#19673 we had
In [10]: e1 = 100*(x**3 + 1)**99
In [11]: e2 = 300*x**2*(x**3 + 1)**99
In [12]: %time e1.equals(e2)
CPU times: user 1.13 s, sys: 9.37 ms, total: 1.14 s
Wall time: 1.15 s
Out[12]: FalseIt seems like the .equals method has gotten faster. Anyone know what's changed?
they have code but it just isn't reviewed and merged
Hello guys , I wanted to know whether there is a way that I could expand
(1+x)**n as a binomial expansion , not sure I could find one . I ask this because I'm working on an issue which involves something like (1+x)**n- x**n, now the issue works perfectly when we use numbers like (1+x)**3 - x**3 and we could solve this through gammasimp() giving 3*x**2 + 3*x + 1 but symbolically not sure how we could approach it . Maybe if we could expand the (1+x)**n as a binomial expansion and cancel out the first term which would always be x**n then the maybe the issue wouldn't be that tough to solve . Currently gammasimp() isn't of much help ! and returns back the same expression !
Yeah @jksuom that works , would surely go for that ! Just wanted to confirm whether we had some method to deal with this . The issue I'm trying to tackle is this
>>> k, n = symbols('k, n', positive=True, integer=True) >>> from sympy import oo
>>> limit((n+1)**k/((n+1)**(k+1) - (n)**(k+1)), n, oo)
oo
>>> limit((n+1)**2/((n+1)**(3) - (n)**(3)), n, oo)
1/3
>>> limit((n+1)**2/((n+1)**(3) - (n)**(3)).gammasimp(), n, oo)
1/3
>>> limit((n+1)**k/((n+1)**(k+1) - (n)**(k+1)).gammasimp(), n, oo)
0
This is somewhat required to solve a somewhat bigger issue i'm trying to approach !
works fine numerically but symbolically should return 1/k+1 , also there is somewhat involvement of
gammasimp() there, so have to get that case correctly too ! Never thought a gammasimp() would alter limits from oo to 0 but it does .Maybe if I find it too buggy and some more places where it the (n+1)**k - n**k combo goes wrong , i'll raise this !
Apparently this arrangement of
(n+1)**k -(n)**k gives the correct answer . I am not sure why this may be happening but obviously it feels a bit strange if different arrangements of the same expression can lead to different answers! The gammasimp of that expression which returns 0 is (-n*n**k + n*(n + 1)**k + (n + 1)**k)
