ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 15 Jul 2018 20:41:18 -0500Finding the generators for automorphisms of a graphhttp://ask.sagemath.org/question/43028/finding-the-generators-for-automorphisms-of-a-graph/ Having a large graph, it will cause memory and kernel issues for SAGE to list all graph automorphisms. Is there a way to find the generators of the automorphisms instead of the whole automorphisms of a graph?ASHSun, 15 Jul 2018 20:41:18 -0500http://ask.sagemath.org/question/43028/Evaluating a list of multivariate equations at random values.http://ask.sagemath.org/question/41662/evaluating-a-list-of-multivariate-equations-at-random-values/I have a list of multivariate equations, there are `o` multivariate equations in the list where `o` is an integer and `v = 2o`, the variables that make up the equations are the generators of `P = PolynomialRing(K,'x',n)` where `n = v + o` so for example if `o = 2` then `v = 4` and `n = 6` so the variables that make up the multivariate equations in the list would be `P.gens() = (x0, x1, x2, x3, x4, x5)`. Now i need to substitute in random values from `GF(q)` for the first `v` variables in each of the multivariate equations in the list so in the example above where `v = 4` random values from `GF(q)`would be substituted in for the variables `x0, x1, x2, x3`in each of the multivariate equations in the list, leaving equations in only two variables `x4 and x5`. I have tried to implement this but i don't really know where to start as i know i am doing something wrong but what i have is the following. If the list of multivariate equations is called `eqn` for example.
for i in range(v):
xi = var('x'+str(i))
eqnsub0 = eqn[i].subs({x[i]:GF(q).random_element()})
I already know this is very wrong as the indexing will already go out of bounds since `v > o` but i don't really know where to start with this. Any help would be great, thanks. DalvirTue, 20 Mar 2018 16:51:34 -0500http://ask.sagemath.org/question/41662/Equivalent of Polynomial.list() for expression involving generator of GaloisFieldhttp://ask.sagemath.org/question/38458/equivalent-of-polynomiallist-for-expression-involving-generator-of-galoisfield/I know that it is possible to use the method list() to get a list with the coefficients of a polynomial. For instance:
sage: S.<x> = PolynomialRing(ZZ, 'x')
sage: (1 - 5*x + 3*x**2 + 2*x**3).list()
[1, -5, 3, 2]
I would like to do something like that with an expression involving a generator of a Galois Field.
For example:
sage: q = 5
sage: m = 2
sage: F.<a> = GF(q**m)
sage: a**9
3*a + 1
So, ideally, I would like to do the following
(a**9).list()
and get
[1, 3]
Is there any simple way to that?Hilder VĂtor Lima PereiraTue, 01 Aug 2017 17:43:08 -0500http://ask.sagemath.org/question/38458/Check if a finitely generated matrix group is finite (works with QQ and not with CC)http://ask.sagemath.org/question/38403/check-if-a-finitely-generated-matrix-group-is-finite-works-with-qq-and-not-with-cc/Dear all, I am a newbie in sage. I would like to check if a finitely generated matrix group is finite. Before to proceed with the calculation on my actual problem (where matrices have complex entries), I have tried a very simple example. Consider the group generated by the matrices [1,0,0,1] and [0,1,1,0], this group is clearly finite. Can somebody explain me why the following code works:
sage: MS = MatrixSpace(QQ, 2, 2)
sage: G = MatrixGroup([MS([1,0,0,1]),MS([0,1,1,0])])
sage: G.is_finite()
True
but if I change the field QQ -> RR (or CC), an error is generated:
sage: MS = MatrixSpace(RR, 2, 2)
sage: G = MatrixGroup([MS([1,0,0,1]),MS([0,1,1,0])])
sage: G.is_finite()
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call last)
<ipython-input-215-0022a668c150> in <module>()
----> 1 G.is_finite()
/Applications/SageMath-7.6.app/Contents/Resources/sage/src/sage/groups/group.pyx in sage.groups.group.Group.is_finite (/Applications/SageMath-7.6.app/Contents/Resources/sage/src/build/cythonized/sage/groups/group.c:2696)()
179 NotImplementedError
180 """
--> 181 return self.order() != infinity
182
183 def is_multiplicative(self):
/Applications/SageMath-7.6.app/Contents/Resources/sage/src/sage/groups/group.pyx in sage.groups.group.Group.order (/Applications/SageMath-7.6.app/Contents/Resources/sage/src/build/cythonized/sage/groups/group.c:2623)()
164 NotImplementedError
165 """
--> 166 raise NotImplementedError
167
168 def is_finite(self):
NotImplementedError:
Is there any way to force the second piece of code to work with matrices with entries in CC?
Thank you in advance.frenkyoTue, 25 Jul 2017 10:22:22 -0500http://ask.sagemath.org/question/38403/