Try q=2 n=4 or q=3 n=3 to see the "error" :) 





























On Thursday, May 14, 2015 at 6:10:19 AM UTC-5, David Joyner wrote:
>
> On Thu, May 14, 2015 at 6:59 AM, Dima Pasechnik <[email protected] 
> <javascript:>> wrote: 
> > The poster has not provided an example producing the error. 
> > One needs to increase q and/or n, as it is mentioned in the post. 
> > 
>
> I missed that. Is it possible that the error is entirely due to the 
> way sagecell writes it to a file for execution in Python, and not the 
> code itself? 
>
> > On Thursday, 14 May 2015 11:32:30 UTC+1, David Joyner wrote: 
> >> 
> >> On Wed, May 13, 2015 at 9:13 PM, Phoenix <[email protected]> 
> wrote: 
> >> > 
> >> > 
> >> > So I have this SAGE code which takes in two integers q and n and it 
> >> > generates ~ (q^3)^(n^2) 0/1 matrices and does a sum of their 
> >> > characteristic 
> >> > polynomials. 
> >> > 
> >> > I got answers for (q = 3, n = 2), (q =2 , n = 3) and (q=2, n=2) 
> >> > 
> >> > For any higher number the code runs for ~1hr and then it says, 
> >> > 
> >> > " 
> >> > 
> >> > Traceback (most recent call last): 
> >> >   File "<stdin>", line 1, in <module> 
> >> >   File "_sage_input_2.py", line 10, in <module> 
> >> >     exec compile(u'open("___code___.py","w").write("# -*- coding: 
> utf-8 
> >> > -*-\\n" + 
> >> > 
> >> > 
> _support_.preparse_worksheet_cell(base64.b64decode("UA=="),globals())+"\\n"); 
>
> >> > execfile(os.path.abspath("___code___.py")) 
> >> >   File "", line 1, in <module> 
> >> > 
> >> >   File "/tmp/tmpPiPIoq/___code___.py", line 2, in <module> 
> >> >     exec compile(u'P 
> >> >   File "", line 1, in <module> 
> >> > 
> >> > " 
> >> > 
> >> > 
> >> > Can someone help understand what is going on? 
> >> > 
> >> > Like any suggestion about how to go about it? 
> >> > 
> >> 
> >> I cannot reproduce this error: 
> >> 
> >> 
> >> q=2; n =2 
> >> rep = [ matrix ([[1, 0, 0, 0], [0, 0, 0, 1], [0, 1, 0, 0], [0, 0, 1, 
> >> 0]] ), matrix ([[1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0], [0, 1, 0, 
> >> 0]] ) ,  matrix ([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1], [0, 0, 1, 
> >> 0]] ) , matrix ( [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 
> >> 1]] ) ,  matrix ( [[1, 0, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1], [0, 1, 0, 
> >> 0]]) , matrix ([[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 
> >> 1]] )  ] 
> >> 
> >> Edge = [(0, 2), (0, 3), (1, 2), (1, 3)] 
> >> 
> >> P = 0 
> >> from itertools import product 
> >> from itertools import izip 
> >> 
> >> for X in product(rep,repeat = len (Edge)): 
> >>     k = izip(Edge,X) 
> >>     M = [[matrix(q^2, q^2, 0)]*(2*n) for _ in range(2*n)] 
> >>     for ((a,b),Y) in k: 
> >>       M[a][b] = Y 
> >>       M[b][a] = Y.inverse() 
> >>     Z = block_matrix(M) 
> >>     P = P + Z.charpoly(x) 
> >> print P 
> >> 
> >> 
> >> gives 
> >> 
> >> 1296*x^16 - 20736*x^14 + 129600*x^12 - 393984*x^10 + 584496*x^8 - 
> >> 362880*x^6 + 62208*x^4 
> >> 
> >> 
> >> > 
> >> > 
> >> > EDIT: 
> >> > 
> >> > This is basically the main time-consuming step. 
> >> > 
> >> > At this point "rep" comes in as a ~q^3 size list of q^2 dimensional 
> 0/1 
> >> > permutation matrices. 
> >> > And "Edge" is a list of integer tuples where each tuple is of the 
> form 
> >> > (a,b) 
> >> > with a,b being from the set {0,1,2,3...,(2n-1)} 
> >> > 
> >> > P = 0 
> >> > from itertools import product 
> >> > from itertools import izip 
> >> > 
> >> > for X in product(rep,repeat = len (Edge)): 
> >> >     k = izip(Edge,X) 
> >> >     M = [[matrix(q^2, q^2, 0)]*(2*n) for _ in range(2*n)] 
> >> >     for ((a,b),Y) in k: 
> >> >       M [a][b] = Y 
> >> >       M [b][a] = Y.inverse() 
> >> >     Z = block_matrix(M) 
> >> >     P = P + Z.charpoly(x) 
> >> > 
> >> > The polynomial P is the final expected answer. 
> >> > 
> >> > (and for any larger value of q and n than the 3 cases mentioned the 
> >> > program 
> >> > basically stops with no output for P and with the above pasted 
> message) 
> >> > 
> >> > -- 
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