// Make newform 245.2.j.e in Magma, downloaded from the LMFDB on 28 March 2024. // To make the character of type GrpDrchElt, type "MakeCharacter_245_j();" // To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_245_j_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_245_2_j_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_245_2_j_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, 0, -1, 0, 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_245_j();" function MakeCharacter_245_j() N := 245; order := 6; char_gens := [197, 101]; v := [3, 2]; // 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_245_j_Hecke();" function MakeCharacter_245_j_Hecke(Kf) N := 245; order := 6; char_gens := [197, 101]; char_values := [[-1, 0, 0, 0], [-1, 0, 1, 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, 2, 0, 0], [0, 1, 0, -1], [2, -1, -2, 0], [0, 0, 0, 0], [0, 0, 3, 0], [0, 0, 0, 1], [0, -7, 0, 7], [0, 0, 0, 0], [0, -6, 0, 0], [5, 0, 0, 0], [0, 0, -2, 0], [0, 2, 0, 0], [2, 0, 0, 0], [0, 0, 0, -4], [0, -3, 0, 0], [0, 6, 0, -6], [0, 0, 10, 0], [8, 0, -8, 0], [0, -2, 0, 2], [-8, 0, 0, 0], [0, 6, 0, -6], [-5, 0, 5, 0], [0, 0, 0, -4], [0, 0, 0, 0], [0, 0, 0, -7], [0, 0, -12, 0], [0, 19, 0, 0], [0, -8, 0, 0], [0, 0, 5, 0], [0, 0, 0, 6], [0, 0, 0, -2], [-22, 0, 22, 0], [0, -12, 0, 12], [10, 0, 0, 0], [10, 0, -10, 0], [0, 0, 13, 0], [0, 18, 0, -18], [0, 14, 0, 0], [0, 0, 0, 3], [0, 9, 0, 0], [0, 0, -20, 0], [-18, 0, 0, 0], [3, 0, -3, 0], [0, 16, 0, -16], [0, 0, 0, -2], [0, 0, -10, 0], [-13, 0, 0, 0], [0, 0, 0, 21], [0, -17, 0, 17], [-10, 0, 10, 0], [0, -16, 0, 0], [-15, 0, 0, 0], [0, 0, -22, 0], [-18, 0, 0, 0], [0, 22, 0, 0], [0, -24, 0, 24], [0, 0, 10, 0], [8, 0, -8, 0], [0, -2, 0, 2], [7, 0, 0, 0], [0, 11, 0, -11], [0, 0, 0, -9], [0, 0, 0, -7], [0, 0, -12, 0], [0, -21, 0, 0], [0, 12, 0, 0], [-12, 0, 12, 0], [0, 0, 0, 18], [0, 18, 0, -18], [20, 0, 0, 0], [0, 11, 0, -11], [-20, 0, 20, 0], [0, 3, 0, -3], [0, 24, 0, 0], [-20, 0, 0, 0], [0, -16, 0, 0], [0, 0, 5, 0], [0, 7, 0, 0], [3, 0, -3, 0], [0, 0, 20, 0], [-30, 0, 0, 0], [-3, 0, 0, 0], [0, 0, 23, 0], [0, 0, 0, 26], [30, 0, -30, 0], [0, 4, 0, 0], [5, 0, 0, 0], [0, -38, 0, 0], [12, 0, 0, 0], [0, 0, 0, 36], [0, 27, 0, 0], [0, 0, -30, 0], [0, -42, 0, 42], [7, 0, 0, 0], [-35, 0, 35, 0], [0, 0, 0, -9], [-30, 0, 30, 0], [0, 0, 28, 0], [0, 4, 0, 0], [-27, 0, 27, 0], [0, 0, 0, -32], [0, 28, 0, -28], [0, -24, 0, 24], [-30, 0, 30, 0], [0, 0, -12, 0], [0, 43, 0, -43], [0, 0, 0, -12], [0, -41, 0, 0], [0, 0, 25, 0], [-8, 0, 0, 0], [0, 27, 0, 0], [0, -44, 0, 44], [0, 0, 0, -22], [0, 0, 10, 0], [37, 0, 0, 0], [0, 0, -22, 0], [0, 0, 0, 1], [0, 8, 0, -8], [0, 4, 0, 0], [15, 0, 0, 0], [0, 0, -12, 0], [0, 0, 0, -24], [0, -43, 0, 0], [0, 16, 0, -16], [8, 0, -8, 0], [-13, 0, 0, 0], [35, 0, -35, 0], [30, 0, -30, 0], [0, 0, 0, 28], [0, -1, 0, 0], [0, 0, -35, 0], [0, 0, 0, -14], [33, 0, -33, 0], [0, 0, 0, -32], [-2, 0, 2, 0], [0, 0, 0, 0], [0, 21, 0, -21], [0, -17, 0, 17], [0, 0, 0, 13], [0, 0, 45, 0], [-38, 0, 0, 0], [23, 0, -23, 0], [0, 26, 0, -26], [0, 0, 0, 18], [0, 0, -30, 0], [-30, 0, 0, 0], [0, 0, 0, -54], [0, -42, 0, 42], [40, 0, -40, 0], [0, 54, 0, 0], [0, 32, 0, 0], [32, 0, 0, 0], [0, 0, 0, 36], [0, -28, 0, 0], [0, 38, 0, -38], [12, 0, 0, 0], [-5, 0, 5, 0], [-50, 0, 50, 0], [0, 0, 0, 13], [0, 0, 48, 0], [0, 42, 0, 0], [0, 0, 0, 6], [0, 0, 0, 8], [-22, 0, 22, 0], [0, -12, 0, 12], [0, 51, 0, -51], [0, 0, 8, 0], [0, 13, 0, -13]]; aps := ConvertToHeckeField(raw_aps); chi := MakeCharacter_245_j_Hecke(Universe(aps)); return ExtendMultiplicatively(weight, aps, chi); end function; // To make the newform (type ModFrm), type "MakeNewformModFrm_245_2_j_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_245_2_j_e(:prec:=4) chi := MakeCharacter_245_j(); 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_245_2_j_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_245_2_j_e( : sign := -1) R := PolynomialRing(Rationals()); chi := MakeCharacter_245_j(); // SetVerbose("ModularSymbols", true); Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign))); Vf := Kernel([<2,R![16, 0, -4, 0, 1]>,<3,R![1, 0, -1, 0, 1]>,<31,R![4, 2, 1]>],Snew); return Vf; end function;