Oh. I see. It's just that the default layout does not like disconnected
graphs at all. Your graph ha many connected components, and it would be
best to print them independently :-)
for cc in CG.connected_components_subgraphs():
cc.show()
Nathann
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Hello,
I am quite new to Sage. I have a science background but am a stranger to
rings, fields and other advanced mathematical topics which seem central in
working with Sage. Having struggled with the issue below for quite a while
though, I decided to post it.
I have a power series f in x1 and
hello,
I was wondering how to ask Sage for the following: given a finite group G,
find the complete list of groups H such that G = H/C_2, where C_2 is a
*central* subgroup of order 2 in H.
If I create a group with say G= gap(SmallGroup(4, 2)) then I can see that
the Extensions method should
Reusing variable names is generally a recipe for confusion:
R.x1,x2=PowerSeriesRing(SR)
P.x1,x2=PolynomialRing(QQ)
Now R and P have variables that print as x1 and x2, but of course they
are still different variables. Now compare
sage: f
x1*x2 + O(x1, x2)^3
sage: f[2]# the degree-2 part
Lame but easy method: Go though all groups with 2*G.Size() elements and
pick out the ones you want.
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Thanks, I thought about this, but I'm not sure how to pick central elements
of order 2 in a group, or more precisely in a group that is given by
gap(SmallGroup(n,i)). I can try C= G.centre() and then get C.generators()
but i'm not sure if I can assume anything about these generators (I doubt
partially answering my own question: for the lame but easy method,
one can do the following. Having a putative group H, try:
for x in [g for g in G.Centre().Elements() if g.Order() == 2]:
Q= G.FactorGroupNC( G.Subgroup([ x ]) ) # no idea why NC
if Q.IdGroup() == what you want
sorry G should be H throughout, in my last post.
2013/1/14 Pierre Guillot pierre.guil...@gmail.com:
partially answering my own question: for the lame but easy method,
one can do the following. Having a putative group H, try:
for x in [g for g in G.Centre().Elements() if g.Order() == 2]:
Thank you. That is a good point although I still do not see how it solves
the issue. Suppose I define f_symb as
f_symb(t1,t2)=t1*t2
to avoid the confusion of using identical variable-names meaning different
things, what would I have to do to convert f_symb to f such that I can do
the
You can't substitute power series into the symbolic ring, since power
series are not objects of the symbolic ring. It just doesn't make sense in
general.
You can substitute power series into polynomials; This also makes
mathematical sense:
sage: f_symb
(t1, t2) |-- t1*t2
sage:
sage: K.p,d,e,N = FractionField(PolynomialRing(QQ,4,'pdeN'))
sage: R.x = K[]
sage: a = x^3-x^-3
sage: b = x^5-x^-5
sage: c = x^8-x^-8
sage: X = p*a + d*b + e*c
sage: f = x^16 *(X^2- N*b*c)
and Sage does not answer. It just hangs and I have to kill the session.
If it would answer I would like to
If I break the computation into smaller pieces it works OK:
sage: K.p,d,e,N = FractionField(PolynomialRing(QQ,4,'pdeN'))
sage: R.x = K[]
sage: a = x^3-x^-3
sage: b = x^5-x^-5
sage: c = x^8-x^-8
sage: X = p*a +d*b + e*c
sage: H = R(x^8 * X)
sage: f = H - N*b*c*x^16
sage: f
-N*x^29 +
oh, never mind, this isn't the same computation as I didn't square X.
On Monday, January 14, 2013 2:54:08 PM UTC-8, Michael Beeson wrote:
If I break the computation into smaller pieces it works OK:
sage: K.p,d,e,N = FractionField(PolynomialRing(QQ,4,'pdeN'))
sage: R.x = K[]
sage: a =
So one problem with the original post was that the thing I was trying to
cast to a polynomial isn't a polynomial.
I should have multiplied by x^32, not x^16. The correct input works
correctly (see below). Still, attempting
to cast a rational function with too big a denominator to a
On Monday, January 14, 2013 2:31:46 PM UTC-8, Michael Beeson wrote:
sage: K.p,d,e,N = FractionField(PolynomialRing(QQ,4,'pdeN'))
Why not just
sage: K.p,d,e,N = PolynomialRing(QQ,4,'pdeN')
With this change, sage doesn't hang (for me). Oh, I see, later you need
field coefficients.
Hi Michael,
On 2013-01-14, Michael Beeson profbee...@gmail.com wrote:
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sage: K.p,d,e,N = FractionField(PolynomialRing(QQ,4,'pdeN'))
sage: R.x = K[]
sage: a = x^3-x^-3
sage: b = x^5-x^-5
sage: c = x^8-x^-8
Rogério Brito rbr...@ime.usp.br writes:
Hi there.
I use a Debian sid/unstable system with Linux kernel for amd64/x86_64, but
with userland being i386.
Thanks for the report. I've seen this issue come up before, I believe.
I'm CCing sage-devel in case someone there knows what to do about it.
On 2013-01-14, Pierre Guillot pierre.guil...@gmail.com wrote:
partially answering my own question: for the lame but easy method,
one can do the following. Having a putative group H, try:
for x in [g for g in G.Centre().Elements() if g.Order() == 2]:
Q= G.FactorGroupNC( G.Subgroup([ x ])
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