// Make newform 2736.2.bm.e in Magma, downloaded from the LMFDB on 29 March 2024. // To make the character of type GrpDrchElt, type "MakeCharacter_2736_bm();" // To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_2736_bm_Hecke();" // To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();" // To make the newform (type ModFrm), type "MakeNewformModFrm_2736_2_bm_e();". // This may take a long time! To see verbose output, uncomment the SetVerbose lines below. // The precision argument determines an initial guess on how many Fourier coefficients to use. // This guess is increased enough to uniquely determine the newform. // To make the Hecke irreducible modular symbols subspace (type ModSym) // containing the newform, type "MakeNewformModSym_2736_2_bm_e();". // This may take a long time! To see verbose output, uncomment the SetVerbose line below. // The default sign is -1. You can change this with the optional parameter "sign". function ConvertToHeckeField(input: pass_field := false, Kf := []) if not pass_field then poly := [1, -1, 1]; Kf := NumberField(Polynomial([elt : elt in poly])); AssignNames(~Kf, ["nu"]); end if; Rfbasis := [Kf.1^i : i in [0..Degree(Kf)-1]]; inp_vec := Vector(Rfbasis)*ChangeRing(Transpose(Matrix([[elt : elt in row] : row in input])),Kf); return Eltseq(inp_vec); end function; // To make the character of type GrpDrchElt, type "MakeCharacter_2736_bm();" function MakeCharacter_2736_bm() N := 2736; order := 6; char_gens := [1711, 2053, 1217, 1009]; v := [3, 6, 6, 1]; // chi(gens[i]) = zeta^v[i] assert UnitGenerators(DirichletGroup(N)) eq char_gens; F := CyclotomicField(order); chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),[F|F.1^e:e in v]); return MinimalBaseRingCharacter(chi); end function; // To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_2736_bm_Hecke();" function MakeCharacter_2736_bm_Hecke(Kf) N := 2736; order := 6; char_gens := [1711, 2053, 1217, 1009]; char_values := [[-1, 0], [1, 0], [1, 0], [0, 1]]; assert UnitGenerators(DirichletGroup(N)) eq char_gens; values := ConvertToHeckeField(char_values : pass_field := true, Kf := Kf); // the value of chi on the gens as elements in the Hecke field F := Universe(values);// the Hecke field chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),values); return chi; end function; function ExtendMultiplicatively(weight, aps, character) prec := NextPrime(NthPrime(#aps)) - 1; // we will able to figure out a_0 ... a_prec primes := PrimesUpTo(prec); prime_powers := primes; assert #primes eq #aps; log_prec := Floor(Log(prec)/Log(2)); // prec < 2^(log_prec+1) F := Universe(aps); FXY := PolynomialRing(F, 2); // 1/(1 - a_p T + p^(weight - 1) * char(p) T^2) = 1 + a_p T + a_{p^2} T^2 + ... R := PowerSeriesRing(FXY : Precision := log_prec + 1); recursion := Coefficients(1/(1 - X*T + Y*T^2)); coeffs := [F!0: i in [1..(prec+1)]]; coeffs[1] := 1; //a_1 for i := 1 to #primes do p := primes[i]; coeffs[p] := aps[i]; b := p^(weight - 1) * F!character(p); r := 2; p_power := p * p; //deals with powers of p while p_power le prec do Append(~prime_powers, p_power); coeffs[p_power] := Evaluate(recursion[r + 1], [aps[i], b]); p_power *:= p; r +:= 1; end while; end for; Sort(~prime_powers); for pp in prime_powers do for k := 1 to Floor(prec/pp) do if GCD(k, pp) eq 1 then coeffs[pp*k] := coeffs[pp]*coeffs[k]; end if; end for; end for; return coeffs; end function; function qexpCoeffs() // To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();" weight := 2; raw_aps := [[0, 0], [0, 0], [0, 0], [-1, 2], [0, 0], [6, -3], [0, 0], [-3, -2], [0, 0], [0, 0], [7, 0], [3, -6], [0, 0], [1, 1], [0, 0], [0, 0], [0, 0], [0, -1], [0, 11], [0, 0], [17, -17], [-17, 17], [0, 0], [0, 0], [8, 8], [0, 0], [-7, 0], [0, 0], [12, 12], [0, 0], [0, 20], [0, 0], [0, 0], [26, -13], [0, 0], [-4, 0], [11, -11], [3, -6], [0, 0], [0, 0], [0, 0], [8, -4], [0, 0], [-7, -7], [0, 0], [-26, 13], [29, -29], [-5, 5], [0, 0], [-7, 0], [0, 0], [0, 0], [2, -1], [0, 0], [0, 0], [0, 0], [0, 0], [10, 10], [26, 0], [0, 0], [6, 6], [0, 0], [16, -16], [0, 0], [0, -22], [0, 0], [-1, 0], [-13, -13], [0, 0], [-37, 0], [0, 0], [0, 0], [-18, 9], [4, -8], [-37, 0], [0, 0], [0, 0], [-35, 35], [0, 0], [-16, 8], [0, 0], [-20, -20], [0, 0], [-22, 11], [13, -13], [0, 0], [0, 0], [-41, 0], [0, 0], [21, -42], [0, 0], [0, 0], [-44, 0], [0, 0], [7, 7], [0, 0], [0, 0], [0, 0], [0, -43], [0, 29], [0, 1], [0, 0], [0, 0], [0, 0], [21, -42], [46, 0], [0, 0], [0, 0], [0, 0], [-1, 2], [-29, 0], [-10, 10], [0, 0], [27, -54], [-30, 15], [0, 0], [29, 29], [0, 0], [0, 0], [0, 0], [-40, 20], [-29, 58], [0, 0], [0, 0], [30, -60], [0, 0], [0, -31], [0, 0], [-31, -31], [-50, 0], [23, 23], [0, 0], [0, -41], [-29, 29], [0, 0], [0, -49], [0, 0], [31, 0], [0, 0], [0, 0], [0, -56], [0, 0], [-28, 14], [0, 0], [13, -26], [0, 0], [-23, 23], [0, 0], [66, -33], [0, 0], [-3, -3], [0, 0], [42, -21], [0, 0], [-40, 40], [0, 0], [35, -70], [0, 0], [0, 61], [0, 0], [0, 0], [0, 0], [7, 7], [0, 0], [0, 0], [0, 0], [-61, 61], [0, 59], [8, 8], [0, 0], [0, 0], [-11, -11], [0, 0], [53, 0], [0, -7], [0, 0], [-70, 35], [0, 0], [-65, 0], [49, -49], [76, -38], [0, 0], [14, -7], [0, 0], [0, 0], [0, 0], [56, -28], [35, -35], [32, -64], [0, 0], [78, -39], [0, 0], [11, 0], [0, 0], [0, 0], [0, 0], [0, -2], [-67, 67], [0, 0], [0, 0], [0, 0], [0, 68], [33, 33], [-27, -27], [0, 0], [0, 0], [76, -38], [0, 0], [0, 0], [-67, 0], [-25, 25], [0, 0], [41, -82], [0, 0], [0, 0], [62, -31], [42, 42], [0, 0], [0, 0], [0, 0], [-70, 35], [-61, 0], [0, 0], [31, 31], [0, 0], [0, -13], [0, 0], [0, 0], [-76, 76], [0, 0], [0, -65], [0, 73], [76, 0], [0, 0], [-38, 76], [0, 0], [43, 0], [0, 0], [0, 0], [0, 0], [0, 0], [-26, 52], [-18, 9], [34, -17], [0, 0], [0, 0], [-76, 38], [0, 0], [79, -79], [0, 0], [29, 0], [0, 0], [0, 0], [-64, 32], [0, 0], [0, 0], [0, 53], [-31, 0], [0, 0], [0, 71], [0, -5], [0, 0], [-7, 7], [43, 43], [0, 0], [13, 0], [0, 0], [0, 0], [0, 43], [0, 0], [-5, 10], [-80, 0], [10, -10], [38, -76], [-34, 17], [-37, -37], [0, 0], [-47, -47], [-98, 49], [0, 0], [0, 0], [30, -60], [0, 0], [41, -82], [38, 38], [0, 0], [17, 0], [0, 0], [27, 27], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [-49, -49], [0, 0], [0, 76], [0, 0], [0, 0], [43, -86], [-70, 70], [0, 0], [94, -47]]; aps := ConvertToHeckeField(raw_aps); chi := MakeCharacter_2736_bm_Hecke(Universe(aps)); return ExtendMultiplicatively(weight, aps, chi); end function; // To make the newform (type ModFrm), type "MakeNewformModFrm_2736_2_bm_e();". // This may take a long time! To see verbose output, uncomment the SetVerbose lines below. // The precision argument determines an initial guess on how many Fourier coefficients to use. // This guess is increased enough to uniquely determine the newform. function MakeNewformModFrm_2736_2_bm_e(:prec:=2) chi := MakeCharacter_2736_bm(); f_vec := qexpCoeffs(); Kf := Universe(f_vec); // SetVerbose("ModularForms", true); // SetVerbose("ModularSymbols", true); S := CuspidalSubspace(ModularForms(chi, 2)); S := BaseChange(S, Kf); maxprec := NextPrime(1999) - 1; while true do trunc_vec := Vector(Kf, [0] cat [f_vec[i]: i in [1..prec]]); B := Basis(S, prec + 1); S_basismat := Matrix([AbsEltseq(g): g in B]); if Rank(S_basismat) eq Min(NumberOfRows(S_basismat), NumberOfColumns(S_basismat)) then S_basismat := ChangeRing(S_basismat,Kf); f_lincom := Solution(S_basismat,trunc_vec); f := &+[f_lincom[i]*Basis(S)[i] : i in [1..#Basis(S)]]; return f; end if; error if prec eq maxprec, "Unable to distinguish newform within newspace"; prec := Min(Ceiling(1.25 * prec), maxprec); end while; end function; // To make the Hecke irreducible modular symbols subspace (type ModSym) // containing the newform, type "MakeNewformModSym_2736_2_bm_e();". // This may take a long time! To see verbose output, uncomment the SetVerbose line below. // The default sign is -1. You can change this with the optional parameter "sign". function MakeNewformModSym_2736_2_bm_e( : sign := -1) R := PolynomialRing(Rationals()); chi := MakeCharacter_2736_bm(); // SetVerbose("ModularSymbols", true); Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign))); Vf := Kernel([<5,R![0, 1]>,<7,R![3, 0, 1]>,<11,R![0, 1]>,<23,R![0, 1]>,<31,R![-7, 1]>],Snew); return Vf; end function;