Rank-nullity theorem states that the rank and the nullity of a matrix add
up to the number of columns of a matrix. In the following example, the
matrix defined over R has 5 columns but its rank and nullity add up to 4.
Is this a bug?
sage: m = matrix(RR,[[1,-1,2,0,3],[2,-1,3,-1,2],[3,0,3,0,6
Hi,
I am doing some symbolic calculus stuff with sage, basically solving some
4th order differential equations. At some point, I substitute some
parameters in order to get numerical results. It seems "subs" is choking on
one particular (big) expression. What could be going wrong? How can I debu
Hello Tristan,
> n = 100; d=3
> load DATA+'my_functions.py'
> coefficients = poly_expand(n,int(n**(1/d)),d)
> R. = ZZ[]
> f = 0
> for c in coefficients:
> f += c*t^d
> d -= 1
> g = f.homogenize('s')
>
> Running this returns "AttributeError: 'GlobalPolynomialRing' object has no
> attribu
Yes automorphisms that pop up along the way are used to prune the
search tree. That's a key feature of McKay's algorithm. Also, you
are correct, checking for isomorphism of two graphs is faster than
computing the canonical forms of each (this is what happens when you
call G.is_isomorphic(H)), but
On 2014-03-04, Tom Boothby wrote:
> They do implement the same basic algorithm. However, Robert worked
> from McKay's paper describing the algorithm, which was approximately
> state-of-the-art when he wrote the paper (but of course, the community
> tends to eschew optimizations as superfluous to
