
// Make newform 507.2.e.l in Magma, downloaded from the LMFDB on 24 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_507_e();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_507_e_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_507_2_e_l();".
// 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_507_2_e_l();".
// 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, -2, 5, 0, 3, -1, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0], [6, -2, 5, -9, 3, -1], [18, -6, 15, -14, 9, -3], [-2, -34, -6, -10, -1, -4], [10, -25, -9, -15, 5, -6]];
    Rf_basisdens := [1, 1, 13, 13, 13, 13];
    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_507_e();"
function MakeCharacter_507_e()
    N := 507;
    order := 3;
    char_gens := [170, 340];
    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_507_e_Hecke();"
function MakeCharacter_507_e_Hecke(Kf)
    N := 507;
    order := 3;
    char_gens := [170, 340];
    char_values := [[1, 0, 0, 0, 0, 0], [0, 0, 0, 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<X, Y> := 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<T> := 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 := [[2, -2, 0, 0, -1, -2], [1, 0, 0, 0, 0, -1], [-2, 0, -1, -1, 0, 0], [0, -1, 1, -1, -1, 0], [0, 2, 0, 0, 3, 0], [0, 0, 0, 0, 0, 0], [0, 1, -1, -2, -2, 0], [0, 1, -1, 0, 0, -2], [2, -1, 0, 0, -5, -2], [-1, 2, 0, 0, 3, 1], [3, 0, 2, -5, 0, 0], [7, 1, 0, 0, 0, -7], [2, 2, 0, 0, 3, -2], [0, 2, -2, -2, -2, 5], [-2, 0, -1, 0, 0, 0], [-8, 0, 4, -3, 0, 0], [0, 2, -2, -2, -2, -2], [0, 5, -5, 6, 6, 8], [7, -3, 0, 0, -7, -7], [0, -2, 2, 5, 5, 1], [2, 0, -3, 9, 0, 0], [3, 0, -3, 3, 0, 0], [-5, 0, 1, -2, 0, 0], [3, -7, 0, 0, -1, -3], [0, 10, -10, -2, -2, 1], [-4, 7, 0, 0, 3, 4], [-2, 0, -4, 4, 0, 0], [4, 4, 0, 0, -3, -4], [0, 0, -10, 5, 0, 0], [0, 1, -1, 2, 2, -7], [-3, -6, 0, 0, 0, 3], [7, 0, 0, 9, 0, 0], [0, -10, 10, 0, 0, 5], [0, 4, -4, -5, -5, 4], [0, 3, -3, 3, 3, 17], [8, 0, 7, 1, 0, 0], [-3, 0, 4, -14, 0, 0], [0, 11, -11, 5, 5, 11], [9, 0, 0, 0, -2, -9], [0, -16, 16, -5, -5, -13], [-4, 13, 0, 0, 1, 4], [-15, 0, 1, -7, 0, 0], [0, -1, 1, -13, -13, -1], [9, 4, 0, 0, -12, -9], [11, 1, 0, 0, -8, -11], [0, -5, 5, 1, 1, -7], [-3, -10, 0, 0, -5, 3], [-14, 12, 0, 0, 7, 14], [0, 8, -8, 8, 8, 11], [-7, 0, 10, -13, 0, 0], [6, 0, 1, -2, 0, 0], [-5, 0, 15, -2, 0, 0], [0, -13, 13, 1, 1, -1], [0, 17, -17, 18, 18, 12], [7, -15, 0, 0, -7, -7], [-17, 17, 0, 0, 11, 17], [0, -1, 1, 8, 8, -8], [-21, -1, 0, 0, 0, 21], [0, -8, 8, 1, 1, 10], [-8, 0, 5, -7, 0, 0], [-14, 13, 0, 0, 14, 14], [0, -15, 15, -17, -17, -12], [7, 0, 0, 1, 0, 0], [-17, 0, 3, 1, 0, 0], [12, 0, -23, 10, 0, 0], [-5, 0, 7, 7, 0, 0], [0, 4, -4, 9, 9, 0], [3, 0, 2, -1, 0, 0], [0, 3, -3, 2, 2, 9], [14, -8, 0, 0, 0, -14], [-3, -11, 0, 0, -21, 3], [15, 0, -19, 7, 0, 0], [9, -1, 0, 0, -11, -9], [0, -16, 16, -1, -1, -10], [-1, -5, 0, 0, 6, 1], [0, -13, 13, 3, 3, -3], [-15, 0, -4, 4, 0, 0], [0, -1, 1, -4, -4, -8], [7, -12, 0, 0, -13, -7], [0, -3, 3, -1, -1, -28], [5, -8, 0, 0, -12, -5], [-4, 0, -1, 6, 0, 0], [11, -7, 0, 0, 9, -11], [0, 1, -1, -14, -14, 6], [-3, 18, 0, 0, 7, 3], [6, 0, 1, -4, 0, 0], [0, 7, -7, 4, 4, -14], [10, -5, 0, 0, 9, -10], [0, 4, -4, -8, -8, 5], [16, 0, -8, -4, 0, 0], [5, 0, 6, 20, 0, 0], [-1, 3, 0, 0, -2, 1], [0, -6, 6, -12, -12, -29], [14, -18, 0, 0, -23, -14], [-6, 0, 18, -16, 0, 0], [0, 9, -9, 21, 21, 4], [-8, 0, 0, 0, -2, 8], [-13, 0, 14, -16, 0, 0], [-22, 15, 0, 0, 17, 22], [-6, 0, -14, -5, 0, 0], [15, 0, 11, 16, 0, 0], [19, -8, 0, 0, 5, -19], [0, -1, 1, -10, -10, 13], [16, -12, 0, 0, -5, -16], [-20, 0, 21, -27, 0, 0], [-9, 0, 1, 4, 0, 0], [-4, 12, 0, 0, 14, 4], [14, 0, -8, 26, 0, 0], [25, 0, 5, 11, 0, 0], [7, -24, 0, 0, -2, -7], [0, -14, 14, -9, -9, -15], [-11, 17, 0, 0, 24, 11], [0, 12, -12, 12, 12, 2], [-6, 0, -11, 22, 0, 0], [0, -27, 27, -14, -14, -31], [0, -27, 27, -9, -9, -28], [0, -29, 29, -8, -8, -8], [-4, 2, 0, 0, 13, 4], [-7, 1, 0, 0, 23, 7], [0, -8, 8, -17, -17, 22], [1, -23, 0, 0, 5, -1], [8, 0, 0, 0, -3, -8], [3, 0, 1, 0, 0, 0], [0, 3, -3, 3, 3, 18], [18, -20, 0, 0, -15, -18], [2, 0, 14, 3, 0, 0], [0, 10, -10, 11, 11, 23], [0, 16, -16, -4, -4, 0], [-3, 0, -25, -2, 0, 0], [-25, 0, 19, -1, 0, 0], [-5, 17, 0, 0, 24, 5], [-4, -17, 0, 0, -16, 4], [28, -1, 0, 0, -9, -28], [-16, 4, 0, 0, -1, 16], [0, -7, 7, 7, 7, -17], [-20, 10, 0, 0, 16, 20], [0, -7, 7, 7, 7, -18], [0, 0, 0, 13, 13, -2], [0, 2, -2, 4, 4, -16], [-5, 2, 0, 0, -2, 5], [28, 0, -19, 26, 0, 0], [16, 6, 0, 0, -29, -16], [0, 3, -3, 21, 21, 22], [-5, 0, -28, -3, 0, 0], [-28, 19, 0, 0, -1, 28], [0, 12, -12, 6, 6, 19], [-4, 0, 11, 5, 0, 0], [-12, 0, -12, -22, 0, 0], [40, 0, -31, 25, 0, 0], [0, 0, 15, 0, 0, 0], [0, -4, 4, -6, -6, 31], [36, -7, 0, 0, -2, -36], [4, 0, -7, -10, 0, 0], [15, 8, 0, 0, -7, -15], [16, 24, 0, 0, -3, -16], [37, 0, -16, 19, 0, 0], [0, -10, 10, 11, 11, 18], [0, 2, -2, -14, -14, 5], [19, 0, -9, 19, 0, 0], [-14, 0, -18, -11, 0, 0], [-28, -8, 0, 0, -11, 28], [0, -9, 9, -25, -25, 7], [9, 0, -25, 28, 0, 0], [0, 28, -28, 18, 18, 17], [7, -9, 0, 0, 16, -7], [3, 0, -9, 27, 0, 0], [-8, -2, 0, 0, -1, 8], [0, 1, -1, -23, -23, -7]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_507_e_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_507_2_e_l();".
// 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_507_2_e_l(:prec:=6)
    chi := MakeCharacter_507_e();
    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_507_2_e_l();".
// 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_507_2_e_l( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_507_e();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![169, -52, 55, -14, 13, -3, 1]>,<5,R![-13, 5, 6, 1]>],Snew);
    return Vf;
end function;