// Make newform 546.2.l.j in Magma, downloaded from the LMFDB on 29 March 2024. // To make the character of type GrpDrchElt, type "MakeCharacter_546_l();" // To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_546_l_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_546_2_l_j();". // 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_546_2_l_j();". // 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 := [25, -5, -4, -1, 1]; Kf := NumberField(Polynomial([elt : elt in poly])); AssignNames(~Kf, ["nu"]); end if; Rf_num := [[1, 0, 0, 0], [-25, -4, 4, 1], [5, 9, 1, -1], [-25, 8, 2, 3]]; Rf_basisdens := [1, 20, 5, 10]; Rf_basisnums := ChangeUniverse([[z : z in elt] : elt in Rf_num], Kf); Rfbasis := [Rf_basisnums[i]/Rf_basisdens[i] : i in [1..Degree(Kf)]]; 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_546_l();" function MakeCharacter_546_l() N := 546; order := 3; char_gens := [365, 157, 379]; v := [3, 3, 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_546_l_Hecke();" function MakeCharacter_546_l_Hecke(Kf) N := 546; order := 3; char_gens := [365, 157, 379]; char_values := [[1, 0, 0, 0], [1, 0, 0, 0], [-1, -1, 0, 0]]; 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, 1, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [-1, -1, 0, 0], [0, -4, 0, 0], [4, 1, 0, 0], [-3, -3, 0, 0], [2, 2, 0, -2], [0, -1, 1, -1], [0, 4, -1, 1], [3, 0, -1, 0], [0, -4, -1, 1], [0, 4, -1, 1], [-1, -1, 0, 3], [2, 0, -2, 0], [5, 0, -2, 0], [-1, -1, 0, 3], [9, 9, 0, 0], [0, -7, -1, 1], [-1, -1, 0, -1], [10, 0, -1, 0], [-8, 0, 0, 0], [1, 0, -3, 0], [0, 5, 1, -1], [-8, -8, 0, 2], [0, 6, 1, -1], [1, 0, 1, 0], [0, -6, -2, 2], [4, 0, -2, 0], [-2, -2, 0, -3], [0, 8, 0, 0], [-7, 0, 1, 0], [-10, -10, 0, -3], [-8, -8, 0, 4], [1, 1, 0, 0], [-4, 0, 4, 0], [-8, 0, 1, 0], [9, 9, 0, 1], [0, 0, 0, 0], [-4, -4, 0, 2], [0, 10, 2, -2], [-4, 0, -3, 0], [-11, -11, 0, 1], [0, -12, 3, -3], [0, -9, 3, -3], [1, 1, 0, -3], [0, 4, -4, 4], [0, 15, 1, -1], [4, 4, 0, 4], [17, 0, -1, 0], [16, 0, -2, 0], [-1, 0, -1, 0], [20, 20, 0, -1], [-9, -9, 0, -1], [0, 15, 0, 0], [0, 4, -4, 4], [18, 18, 0, 0], [0, 21, -1, 1], [-2, -2, 0, -3], [-8, 0, -3, 0], [0, -18, -2, 2], [14, 14, 0, 1], [-10, 0, 2, 0], [6, 0, -2, 0], [-8, 0, 6, 0], [1, 0, -2, 0], [-4, -4, 0, 0], [-4, 0, 1, 0], [-22, -22, 0, -2], [0, -5, 7, -7], [0, -11, 2, -2], [16, 0, -4, 0], [0, 9, -1, 1], [-14, -14, 0, -3], [0, -20, 0, 0], [12, 12, 0, -8], [1, 0, -6, 0], [-19, -19, 0, -1], [0, 2, 1, -1], [0, 0, 0, 7], [0, -1, 5, -5], [4, 0, 1, 0], [0, -9, 1, -1], [6, 6, 0, 1], [0, -4, -4, 4], [26, 0, 2, 0], [2, 2, 0, 4], [0, -17, 0, 0], [-2, -2, 0, 5], [-2, 0, -2, 0], [-21, 0, 3, 0], [0, 20, 0, 0], [-16, -16, 0, 4], [0, 8, -4, 4], [-19, 0, -3, 0], [4, 4, 0, 4], [0, -26, -3, 3], [-8, 0, -3, 0], [0, 8, 8, -8], [4, 0, 5, 0], [20, 0, -4, 0], [0, -1, 8, -8], [-24, -24, 0, 0], [0, 22, 4, -4], [-19, 0, 1, 0], [-12, 0, 5, 0], [0, -21, -7, 7], [13, 0, -2, 0], [-15, 0, 1, 0], [0, -12, -1, 1], [-19, -19, 0, 1], [0, 8, -5, 5], [-10, -10, 0, -7], [10, 0, -6, 0], [12, 12, 0, 4], [-6, -6, 0, -3], [-10, -10, 0, 10], [0, 18, 2, -2], [0, -5, -9, 9], [22, 22, 0, -2], [0, 27, 4, -4], [0, -1, 4, -4], [-8, 0, -6, 0], [30, 30, 0, -6], [0, 8, 0, 0], [-15, 0, 7, 0], [26, 26, 0, 5], [8, 8, 0, 0], [7, 0, 3, 0], [-7, 0, -6, 0], [0, -45, 1, -1], [0, -17, -3, 3], [0, -10, 2, -2], [0, -26, 0, 0], [14, 14, 0, -8], [0, 16, -6, 6], [38, 38, 0, -4], [-4, -4, 0, -4], [-8, -8, 0, -2], [0, 14, 1, -1], [-12, 0, 4, 0], [0, 11, -1, 1], [24, 24, 0, -4], [-12, 0, 4, 0], [0, -32, 3, -3], [-22, -22, 0, 10], [-23, 0, 2, 0], [-24, 0, -3, 0], [-2, 0, -6, 0], [-16, 0, 12, 0], [8, 8, 0, -1], [0, -7, -2, 2], [11, 0, 11, 0], [0, 38, -2, 2], [0, -27, 3, -3], [-8, 0, -4, 0], [-14, -14, 0, -6], [-45, -45, 0, -2], [32, 0, -3, 0], [12, 0, 6, 0], [0, 8, 4, -4], [-6, -6, 0, 4], [-10, 0, -2, 0], [7, 7, 0, -13], [0, 46, 5, -5], [-6, 0, 14, 0], [0, 6, 10, -10], [21, 21, 0, -4]]; aps := ConvertToHeckeField(raw_aps); chi := MakeCharacter_546_l_Hecke(Universe(aps)); return ExtendMultiplicatively(weight, aps, chi); end function; // To make the newform (type ModFrm), type "MakeNewformModFrm_546_2_l_j();". // 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_546_2_l_j(:prec:=4) chi := MakeCharacter_546_l(); f_vec := qexpCoeffs(); Kf := Universe(f_vec); // SetVerbose("ModularForms", true); // SetVerbose("ModularSymbols", true); S := CuspidalSubspace(ModularForms(chi, 2)); S := BaseChange(S, Kf); maxprec := NextPrime(997) - 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_546_2_l_j();". // 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_546_2_l_j( : sign := -1) R := PolynomialRing(Rationals()); chi := MakeCharacter_546_l(); // SetVerbose("ModularSymbols", true); Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign))); Vf := Kernel([<5,R![-14, -1, 1]>,<11,R![16, -4, 1]>],Snew); return Vf; end function;