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
How should I be reading the first case? Where does the scalar 0.07... comes from? What the meaning for arg() function?
for
E[X*Y] = E[X]*E[Y] I was expecting E[X]=0.1 then E[X]*E[Y] = 0.1*pdf(Y) which is closer the otherwise case represented in the screen shot above, without the 0.07..., scalar which haven't figured out where it came from?
The arg is the complex argument. If you set
symbols('mu sigma', real=True) it will assume the arguments are real and simplify
@asmeurer thanks a lot, that makes sense now! It seems that sometimes is
evalf() and others just evaluating using some argument stats.density(X)(x). Another issue that seems common is the sympy console after activation sympy.init_session() throws an error whenever using the python function locals(). Also, in sympy console executing sympy.stats.Normal(...) doesn't recognise the submodule stats, one has to separately import each submodule. Are there any ways to overcome these issues? Thanks!
Equivalent(
Interval(b - epsilon, b + epsilon, True, True),
ConditionSet(y, Abs(y - b) < epsilon, Reals)
)
Anyone willing to help me understand why this doesn't return a boolean True? Are there steps that I'm missing?
I'm a sympy learner & trying out lots of the modules. Would like to contribute at some point but still got a lot to learn.
Interval(b - epsilon, b + epsilon, True, True),
ConditionSet(y, Abs(y - b) < epsilon, Reals)
)
Anyone willing to help me understand why this doesn't return a boolean True? Are there steps that I'm missing?
I'm a sympy learner & trying out lots of the modules. Would like to contribute at some point but still got a lot to learn.
Hey, I'm new to Sympy.
I'm trying to find a minimum to a function under some constraints. The function has two variables: x,y, and two parameters: l < 0 and u > 0.
The function is:0.5*u**2 - 1.0*y**2/(1 - x)**2 + 1.0*y*(y/(1 - x) + y/x)/(1 - x) + 0.5*(-l - y/x)*(-l*x - y) - 0.5*(u + y/x)*(u*x + y)
and the constraints are:(y >= 1.0e-6) & (l*x + y <= 1.0e-6) & (u*x + y <= u + 1.0e-6)
(l,u parameters == are known at the time of solving. I have to find x,y which gives a minimum given some l,u assignments)
What is the best approach to solve it? Should I use Sympy or other tools?
Thanks!
I'm working with generating functions in sympy and trying to improve performance by adding
O(x**N) in various places. I'm seeing pretty surprising results, for example (Sum(5*6**(-n)*x**n/2, (n, 1, 10)) + Rational("1/2") + O(x**11)).doit() takes way longer than (Sum(5*6**(-n)*x**n/2, (n, 1, 10)).doit() + Rational("1/2") + O(x**11)).doit(). The difference is the doit() on the Sum before adding the order term. I'm also seeing some oddities when raising a polynomial with an order term to a power. Is there any guidance or something I can read to understand what's going on here and how to use order terms to be efficient?
You might try using the series() method rather than using an order term, although both should work.
Looks like the series method is for getting a series expansion of a function. I'm calculating my coefficients directly from a recurrence relation. I'm not sure I could easily come up with a function whose expansion would match what I'm looking for. I think I got my issue sorted by using
doit() on my Sums and instead of raising my polynomials to a power, doing a for loop with p_n = expand(p_n * p_1). It's not elegant, but it completes in seconds rather than OOMing my machine after several minutes. I'd guess the order term is evaluated at the end of raising something to the nth term.
5 replies
Hello !!
I am Utkarsh Upadhyay, and I am currently a second-year Computer Science Undergraduate at IIIT Hyderabad. I want to make contributions to this organization and would love to continue contributing for GSoC 2021. I would request the mentors and experienced developers to please guide me throughout the process.
Thanks
I am Utkarsh Upadhyay, and I am currently a second-year Computer Science Undergraduate at IIIT Hyderabad. I want to make contributions to this organization and would love to continue contributing for GSoC 2021. I would request the mentors and experienced developers to please guide me throughout the process.
Thanks
I don't know if this equation can be solved in closed form. You can try substituting
phi0 for 10*phi1 in the first equation.
But even then, solve() can't solve it.
There might be a solution in terms of LambertW, but if there is, solve() doesn't know how to find it, even after rewriting the equation in terms of
exp
@asmeurer I would be happy with a numerical solution. I currently am using
scipy.optimize.fsolve but I have to rewrite the equation every time. Sometimes I' m given eta and sometimes phi. With symbolic computation I could have prevented typing the expression and and given two values of phi and an eta, I could have found the eta at another fi and vice versa for two values of eta and a phi.
Hello! I was wondering if anyone could lead me to where I can learn more about Sympy objects (performing research to see if one can pry apart a SymPy object) , or it's data structure. I've looked a lot at the documentation and wiki, but there seems to be a lot of 'how-tos' and not necessarily information about the objects themselves. Thanks in advance!
Could someone help me understand the syntax behind this test case in test_coordsysrect.py (vector module)?
I'm primarily confused by the backslash then indent
*newline
I want to import euler's constant (e) in a file in one of the modules. Can someone help me out with it?
Also, I made some changes to my clone of sympy, and i wanted to import this clone as a library and write some code with it (to test the changes). How should I proceed?
I need to use my clone as a library as I am getting an assertion error for changes made in the function, and I have no clue what is the actual output given by the new function.
From the docstring of Exp1:
The transcendental number `e = 2.718281828\ldots` is the base of the
natural logarithm and of the exponential function, `e = \exp(1)`.
Sometimes called Euler's number or Napier's constant.
Exp1 is a singleton, and can be accessed by ``S.Exp1``,
or can be imported as ``E``.
Examples
========
>>> from sympy import exp, log, E
>>> E is exp(1)
True
>>> log(E)
1
If someone could help me out with the second doubt, that would be great.