Cremona modular symbols#
- class sage.libs.eclib.homspace.ModularSymbols#
Bases:
object
Class of Cremona Modular Symbols of given level and sign (and weight 2).
EXAMPLES:
sage: M = CremonaModularSymbols(225) sage: type(M) <class 'sage.libs.eclib.homspace.ModularSymbols'>
- dimension()#
Return the dimension of this modular symbols space.
EXAMPLES:
sage: M = CremonaModularSymbols(1234, sign=1) sage: M.dimension() 156
- hecke_matrix(p, dual=False, verbose=False)#
Return the matrix of the
p
-th Hecke operator acting on this space of modular symbols.The result of this command is not cached.
INPUT:
p
– a prime numberdual
– (default: False) whether to compute the Heckeoperator acting on the dual space, i.e., the transpose of the Hecke operator
verbose
– (default: False) print verbose output
OUTPUT:
(matrix) If
p
divides the level, the matrix of the Atkin-Lehner involution \(W_p\) atp
; otherwise the matrix of the Hecke operator \(T_p\),EXAMPLES:
sage: M = CremonaModularSymbols(37) sage: t = M.hecke_matrix(2); t 5 x 5 Cremona matrix over Rational Field sage: print(t.str()) [ 3 0 0 0 0] [-1 -1 1 1 0] [ 0 0 -1 0 1] [-1 1 0 -1 -1] [ 0 0 1 0 -1] sage: t.charpoly().factor() (x - 3) * x^2 * (x + 2)^2 sage: print(M.hecke_matrix(2, dual=True).str()) [ 3 -1 0 -1 0] [ 0 -1 0 1 0] [ 0 1 -1 0 1] [ 0 1 0 -1 0] [ 0 0 1 -1 -1] sage: w = M.hecke_matrix(37); w 5 x 5 Cremona matrix over Rational Field sage: w.charpoly().factor() (x - 1)^2 * (x + 1)^3 sage: sw = w.sage_matrix_over_ZZ() sage: st = t.sage_matrix_over_ZZ() sage: sw^2 == sw.parent()(1) True sage: st*sw == sw*st True
- is_cuspidal()#
Return whether or not this space is cuspidal.
EXAMPLES:
sage: M = CremonaModularSymbols(1122); M.is_cuspidal() 0 sage: M = CremonaModularSymbols(1122, cuspidal=True); M.is_cuspidal() 1
- level()#
Return the level of this modular symbols space.
EXAMPLES:
sage: M = CremonaModularSymbols(1234, sign=1) sage: M.level() 1234
- number_of_cusps()#
Return the number of cusps for \(\Gamma_0(N)\), where \(N\) is the level.
EXAMPLES:
sage: M = CremonaModularSymbols(225) sage: M.number_of_cusps() 24
- sign()#
Return the sign of this Cremona modular symbols space. The sign is either 0, +1 or -1.
EXAMPLES:
sage: M = CremonaModularSymbols(1122, sign=1); M Cremona Modular Symbols space of dimension 224 for Gamma_0(1122) of weight 2 with sign 1 sage: M.sign() 1 sage: M = CremonaModularSymbols(1122); M Cremona Modular Symbols space of dimension 433 for Gamma_0(1122) of weight 2 with sign 0 sage: M.sign() 0 sage: M = CremonaModularSymbols(1122, sign=-1); M Cremona Modular Symbols space of dimension 209 for Gamma_0(1122) of weight 2 with sign -1 sage: M.sign() -1
- sparse_hecke_matrix(p, dual=False, verbose=False, base_ring='ZZ')#
Return the matrix of the
p
-th Hecke operator acting on this space of modular symbols as a sparse Sage matrix overbase_ring
. This is more memory-efficient than creating a Cremona matrix and then applying sage_matrix_over_ZZ with sparse=True.The result of this command is not cached.
INPUT:
p
– a prime numberdual
– (default: False) whether to compute the Heckeoperator acting on the dual space, i.e., the transpose of the Hecke operator
verbose
– (default: False) print verbose output
OUTPUT:
(matrix) If
p
divides the level, the matrix of the Atkin-Lehner involution \(W_p\) atp
; otherwise the matrix of the Hecke operator \(T_p\),EXAMPLES:
sage: M = CremonaModularSymbols(37) sage: t = M.sparse_hecke_matrix(2); type(t) <class 'sage.matrix.matrix_integer_sparse.Matrix_integer_sparse'> sage: print(t) [ 3 0 0 0 0] [-1 -1 1 1 0] [ 0 0 -1 0 1] [-1 1 0 -1 -1] [ 0 0 1 0 -1] sage: M = CremonaModularSymbols(5001) sage: T = M.sparse_hecke_matrix(2) sage: U = M.hecke_matrix(2).sage_matrix_over_ZZ(sparse=True) sage: print(T == U) True sage: T = M.sparse_hecke_matrix(2, dual=True) sage: print(T == U.transpose()) True sage: T = M.sparse_hecke_matrix(2, base_ring=GF(7)) sage: print(T == U.change_ring(GF(7))) True
This concerns an issue reported on github issue #21303:
sage: C = CremonaModularSymbols(45, cuspidal=True,sign=-1) sage: T2a = C.hecke_matrix(2).sage_matrix_over_ZZ() sage: T2b = C.sparse_hecke_matrix(2) sage: print(T2a == T2b) True