
// Make newform 2736.2.s.z in Magma, downloaded from the LMFDB on 17 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_2736_s();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_2736_s_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_s_z();".
// 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_s_z();".
// 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 := [27, -9, -6, 3, -2, -1, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0], [9, 21, -9, 1, -4, 1], [36, 12, 0, -2, -1, -2], [-18, 12, -9, -2, 8, -2], [45, 24, 18, 14, -2, -4], [-153, -6, 36, -8, 5, 10]];
    Rf_basisdens := [1, 27, 27, 27, 27, 27];
    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_2736_s();"
function MakeCharacter_2736_s()
    N := 2736;
    order := 3;
    char_gens := [1711, 2053, 1217, 1009];
    v := [3, 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_2736_s_Hecke();"
function MakeCharacter_2736_s_Hecke(Kf)
    N := 2736;
    order := 3;
    char_gens := [1711, 2053, 1217, 1009];
    char_values := [[1, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0], [-1, 0, 1, 0, 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<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 := [[0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 1, 1, 0, 0, 0], [0, -1, 0, -1, 0, 0], [0, 1, 0, 1, 1, 0], [0, 0, 0, 0, 0, 1], [0, 0, 0, 0, 0, 0], [-1, 1, 1, 1, 0, 1], [-4, 0, 4, 1, 0, -1], [2, 0, -2, 2, 0, 0], [-5, 1, 0, 1, 1, 0], [-1, 0, 0, 0, 0, 0], [0, -2, -2, 0, 0, 0], [0, -1, -1, 0, -1, 1], [6, 0, -6, 0, 0, 0], [-3, 0, 3, -3, 0, 0], [0, 1, 0, 0, 1, -1], [-4, 0, 4, 2, 0, 1], [2, 0, -2, -1, 0, 2], [0, -2, 6, 0, -2, 2], [0, -2, -7, 0, 0, 0], [0, -1, 3, 0, 1, -1], [-2, 0, 0, 0, 2, 0], [-5, 0, 5, 1, 0, 0], [0, -2, -1, 0, 3, -3], [8, 0, -8, 0, 0, -2], [4, 5, 0, 5, 2, 0], [-2, 4, 0, 4, 0, 0], [0, 4, 7, 0, 1, -1], [3, -1, 0, -1, 2, 0], [10, 0, -10, 2, 0, 0], [0, -2, 4, 0, 0, 0], [6, 0, -6, 2, 0, 2], [-11, 0, 11, -5, 0, -1], [0, -3, 3, 0, 0, 0], [-4, 2, 0, 2, -2, 0], [0, 2, -7, 0, -2, 2], [-8, -1, 0, -1, 2, 0], [-6, 0, 6, -5, 0, 1], [0, -2, 8, 0, 2, -2], [-4, 3, 0, 3, 1, 0], [-5, 0, 5, 2, 0, -1], [-6, -3, 0, -3, -3, 0], [0, 2, 8, 0, 1, -1], [-19, 1, 0, 1, 2, 0], [-11, 0, 11, -3, 0, 1], [0, -7, -1, 0, -1, 1], [0, 5, -5, 0, 3, -3], [6, -1, 0, -1, -1, 0], [0, 0, 0, 0, -1, 0], [0, 0, 10, 0, -4, 4], [-6, 1, 0, 1, 1, 0], [-9, 0, 9, -2, 0, 2], [-6, 0, 6, 2, 0, 2], [-1, 0, 1, 3, 0, 4], [0, -2, -6, 0, -2, 2], [0, 5, -3, 0, 2, -2], [0, 4, -6, 0, 6, -6], [1, -2, 0, -2, 5, 0], [-13, 0, 13, -3, 0, -2], [0, 0, 10, 0, -2, 2], [2, 4, 0, 4, -4, 0], [0, 2, 3, 0, 1, -1], [4, 1, 0, 1, -3, 0], [-11, 0, 11, 0, 0, 3], [-15, 0, 15, -1, 0, 2], [15, 1, 0, 1, -1, 0], [0, 0, -8, 0, -3, 3], [0, 1, -18, 0, 1, -1], [10, 4, 0, 4, -1, 0], [-17, -7, 0, -7, -2, 0], [0, 4, 2, 0, 2, -2], [-7, 0, 7, -1, 0, 5], [11, 2, 0, 2, -1, 0], [-9, -1, 0, -1, -3, 0], [0, 7, -8, 0, 3, -3], [15, 0, -15, -3, 0, -6], [0, 8, 4, 0, -1, 1], [0, -1, -7, 0, 0, 0], [-19, 0, 19, 4, 0, 3], [2, 3, 0, 3, 1, 0], [0, -4, 1, 0, -1, 1], [-6, 0, 6, -4, 0, -4], [-10, 0, 10, -8, 0, -3], [0, 1, 10, 0, -4, 4], [12, 0, -12, -2, 0, -2], [8, 10, 0, 10, 2, 0], [18, -4, 0, -4, 1, 0], [0, 5, 9, 0, 2, -2], [-2, -9, 0, -9, 0, 0], [-14, -6, 0, -6, -4, 0], [4, 0, -4, 6, 0, -4], [4, -2, 0, -2, -2, 0], [0, -6, 2, 0, -2, 2], [0, -11, -2, 0, 2, -2], [-12, 0, 12, -2, 0, -2], [-16, 0, 16, 0, 0, -2], [-23, 3, 0, 3, -4, 0], [-4, 0, 4, 7, 0, -2], [-5, 0, 5, 6, 0, -6], [-11, 0, 11, -9, 0, 1], [12, 0, -12, -6, 0, 0], [-4, -4, 0, -4, -6, 0], [12, 14, 0, 14, 2, 0], [4, 5, 0, 5, 2, 0], [-9, -8, 0, -8, -3, 0], [0, 5, -2, 0, -5, 5], [3, 0, -3, -5, 0, -2], [30, 0, -30, 5, 0, -1], [4, 4, 0, 4, 5, 0], [-3, -1, 0, -1, -3, 0], [0, 2, 3, 0, 3, -3], [5, 0, -5, -9, 0, 4], [4, 1, 0, 1, -2, 0], [10, 0, -10, -3, 0, -2], [0, -2, 32, 0, -4, 4], [0, 1, -34, 0, -2, 2], [-6, -6, 0, -6, 0, 0], [-14, 0, 0, 0, -4, 0], [-22, 0, 22, -11, 0, -1], [-6, 0, 6, 0, 0, 4], [-10, 8, 0, 8, -1, 0], [10, -4, 0, -4, -8, 0], [18, -7, 0, -7, 5, 0], [34, -4, 0, -4, 2, 0], [0, -5, -21, 0, 4, -4], [-14, 0, 14, 2, 0, 5], [0, 5, 2, 0, 9, -9], [0, 11, -1, 0, -7, 7], [-11, 2, 0, 2, -3, 0], [0, 11, 24, 0, 4, -4], [0, -7, 24, 0, -7, 7], [-14, 0, 14, 3, 0, 4], [0, 10, -8, 0, 7, -7], [19, -7, 0, -7, 4, 0], [15, 0, -15, -8, 0, 2], [-18, 0, 18, -6, 0, -6], [-2, 9, 0, 9, 0, 0], [-24, -8, 0, -8, -2, 0], [-29, -5, 0, -5, 0, 0], [-10, 0, 10, -10, 0, -4], [0, 0, 0, -6, 0, 6], [10, 0, -10, -10, 0, 0], [28, 0, -28, 6, 0, 2], [-16, 2, 0, 2, -7, 0], [0, -5, -6, 0, -5, 5], [0, 12, 5, 0, 8, -8], [0, 0, -6, 0, 0, 0], [-10, 0, 10, 3, 0, 6], [-10, 0, 0, 0, 4, 0], [0, -8, 13, 0, -8, 8], [-1, 1, 0, 1, 2, 0], [-3, 0, 3, 3, 0, -7], [-8, 0, 8, 7, 0, 3], [0, -12, 4, 0, 4, -4], [-10, 10, 0, 10, -4, 0], [10, -5, 0, -5, -8, 0], [0, 3, -29, 0, -4, 4], [10, 0, -10, 10, 0, 7], [14, 0, -14, 8, 0, 6], [0, -2, 8, 0, -4, 4], [0, -5, 17, 0, -4, 4], [0, 1, 7, 0, 5, -5], [0, 4, 0, 0, 10, -10], [-18, -6, 0, -6, 6, 0], [0, 11, 20, 0, 3, -3], [0, 11, -5, 0, 3, -3], [-47, 0, 47, 2, 0, 2], [0, 8, 30, 0, 0, 0], [6, 0, -6, 2, 0, -4], [-14, 1, 0, 1, 3, 0], [0, 10, -4, 0, -3, 3], [0, -4, 8, 0, 6, -6], [-8, 4, 0, 4, -1, 0], [38, 0, -38, 7, 0, 4], [-20, 0, 20, 8, 0, -2], [-23, 0, 23, 9, 0, -5], [0, 0, -26, 0, -4, 4], [-6, 11, 0, 11, 6, 0], [0, -2, 15, 0, -4, 4], [-31, 0, 31, 2, 0, -1], [-6, -8, 0, -8, -2, 0], [-17, 0, 17, 8, 0, 8], [0, -3, 33, 0, 0, 0], [0, 16, 0, 16, 10, 0], [-2, 0, 0, 0, -4, 0], [9, 0, -9, 8, 0, 3], [0, -1, 20, 0, -4, 4], [17, 4, 0, 4, 7, 0], [-16, 13, 0, 13, -7, 0], [17, 0, -17, -4, 0, -2], [20, 0, -20, -2, 0, 2], [11, -1, 0, -1, -11, 0], [0, 6, -8, 0, -4, 4], [6, 0, -6, 1, 0, 1], [40, 0, -40, -2, 0, -6], [7, 0, -7, 10, 0, -5], [0, -6, -25, 0, 2, -2], [-24, -2, 0, -2, -2, 0], [2, -10, 0, -10, -6, 0], [-17, 0, 17, 5, 0, -8], [-1, 0, 1, 18, 0, 9], [0, -10, 6, 0, -3, 3], [0, -20, -14, 0, -5, 5], [0, -19, -24, 0, -1, 1], [18, 0, -18, 2, 0, -4], [28, 0, -28, -2, 0, -10], [20, 0, -20, -6, 0, -2], [0, -4, -10, 0, 6, -6], [20, -11, 0, -11, 6, 0], [0, 8, -16, 0, 7, -7], [0, 0, 0, 16, 0, 10], [7, 13, 0, 13, 7, 0], [-18, 0, 18, -3, 0, 3], [-24, -7, 0, -7, -1, 0], [13, 0, -13, -10, 0, 2], [0, -2, -16, 0, -2, 2], [-9, 15, 0, 15, 12, 0], [-12, -6, 0, -6, 6, 0], [0, 1, -3, 0, -2, 2], [-40, 0, 40, -2, 0, 3], [-16, -15, 0, -15, -4, 0], [0, 5, -9, 0, 14, -14], [0, -7, 30, 0, -2, 2], [0, -6, 26, 0, -8, 8], [4, 0, -4, 0, 0, -9], [18, -4, 0, -4, -4, 0], [0, 9, -36, 0, 9, -9], [0, 2, 26, 0, -4, 4], [-24, 6, 0, 6, 6, 0], [-27, 0, 27, 4, 0, 2], [-18, 0, 18, -1, 0, -2], [-49, 2, 0, 2, 1, 0], [18, -14, 0, -14, 4, 0], [-28, 6, 0, 6, 14, 0], [0, 1, 26, 0, -1, 1], [-10, -8, 0, -8, 1, 0], [-28, 0, 0, 0, 4, 0], [0, 14, -12, 0, 14, -14], [18, 0, -18, -7, 0, 5], [0, -15, -6, 0, -3, 3], [-18, -2, 0, -2, -4, 0], [-11, 0, 11, -9, 0, 7], [-11, 0, 11, 0, 0, 12], [0, 9, -7, 0, -2, 2], [4, -16, 0, -16, -8, 0], [-20, 0, 20, -8, 0, -4], [-20, 0, 20, -15, 0, 5], [0, 7, -20, 0, 2, -2], [26, 0, -26, 5, 0, 3], [17, -12, 0, -12, 0, 0], [0, -7, -25, 0, 6, -6], [-44, -8, 0, -8, 0, 0], [3, 0, -3, -6, 0, -5], [0, 13, 33, 0, -2, 2], [30, 0, -30, 14, 0, -4], [26, 0, -26, 10, 0, -3], [-10, -19, 0, -19, 4, 0], [0, 4, 24, 0, 4, -4], [0, 0, 0, -10, 0, -3], [-16, 0, 16, 7, 0, -2], [0, -13, 16, 0, -5, 5], [0, -2, -14, 0, -11, 11], [0, 4, -3, 0, 8, -8], [21, 0, -21, 5, 0, 2], [18, -3, 0, -3, -14, 0], [-14, -16, 0, -16, -2, 0], [-32, 10, 0, 10, 6, 0], [-20, 0, 20, -9, 0, -2], [46, 0, -46, -10, 0, 4], [-6, -18, 0, -18, 5, 0], [-19, -6, 0, -6, -1, 0], [0, -8, 14, 0, 0, 0], [-12, -4, 0, -4, 0, 0], [-6, 0, 6, 14, 0, -3], [0, -3, -11, 0, 1, -1], [12, -18, 0, -18, 12, 0], [0, 14, 24, 0, 9, -9], [-27, 0, 27, 14, 0, -6], [-24, 0, 24, 16, 0, -2], [-12, -1, 0, -1, -7, 0], [-4, 18, 0, 18, 14, 0], [0, 0, 0, -7, 0, 11], [37, 0, 0, 0, -2, 0], [0, -10, 45, 0, -5, 5], [0, 0, 0, 6, 0, 6], [35, -8, 0, -8, -2, 0], [-27, 0, 27, 13, 0, 16], [0, -7, -43, 0, -1, 1], [20, 4, 0, 4, 2, 0], [14, -18, 0, -18, -14, 0], [24, 7, 0, 7, -11, 0], [-2, 0, 2, 6, 0, 2], [36, 0, 0, 0, 6, 0], [0, 2, 13, 0, 14, -14], [15, 1, 0, 1, 4, 0], [34, 0, -34, 18, 0, 4], [0, -21, -35, 0, -4, 4], [0, 9, 42, 0, 3, -3], [-26, -21, 0, -21, 0, 0], [0, 2, -23, 0, 5, -5], [0, 0, 60, 0, -6, 6], [16, 0, -16, 11, 0, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_2736_s_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_2736_2_s_z();".
// 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_s_z(:prec:=6)
    chi := MakeCharacter_2736_s();
    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_s_z();".
// 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_s_z( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_2736_s();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<5,R![144, -96, 88, -8, 12, -2, 1]>,<7,R![-3, -9, -1, 1]>,<11,R![-36, -24, 0, 1]>,<13,R![9, 63, 438, 27, 22, -1, 1]>],Snew);
    return Vf;
end function;