#5520: [with patch; needs review] implement Pizer's algorithm for computing
Brandt
Modules and Brandt Matrices
---------------------------+------------------------------------------------
Reporter: was | Owner: craigcitro
Type: enhancement | Status: new
Priority: major | Milestone: sage-3.4.1
Component: modular forms | Keywords:
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Comment(by tornaria):
The construction of the brandt matrix at the bottom of
{{{_compute_hecke_matrix_brandt()}}} can be accelerated quite a lot by
this:
{{{
B = self._brandt_series_vectors(2*n+10)
m = len(B)
K = self.base_ring()
- return matrix(K, [[K(B[i][j][n]) for i in range(m)] for j in
range(m)], sparse=sparse)
+ Bmat = matrix(K, m, m, sparse=sparse)
+ for i in range(m):
+ for j in range(m):
+ Bmat[i,j] = K(B[j][i][n])
+ return Bmat
}}}
In the example above (p=20011) it would still take 5 hours to compute the
first brandt matrix, but I expect only 5 seconds (instead of 1000) to
return the second brandt matrix (assuming the coefficients were already
precomputed).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5520#comment:17>
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