
// Make newform 441.2.f.d in Magma, downloaded from the LMFDB on 25 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_441_f();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_441_f_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_441_2_f_d();".
// 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_441_2_f_d();".
// 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 := [3, -12, 19, -15, 10, -3, 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, 0, 1, 5, -1, 1], [0, -3, 2, -5, 1, -1], [6, -21, 19, -16, 5, -2], [-9, 33, -22, 19, -5, 2]];
    Rf_basisdens := [1, 1, 3, 3, 3, 3];
    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_441_f();"
function MakeCharacter_441_f()
    N := 441;
    order := 3;
    char_gens := [344, 199];
    v := [1, 3];
    // 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_441_f_Hecke();"
function MakeCharacter_441_f_Hecke(Kf)
    N := 441;
    order := 3;
    char_gens := [344, 199];
    char_values := [[0, 0, 0, 0, 1, 0], [1, 0, 0, 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, -1, -1, -1, 0, 1], [0, 0, -1, -1, 0, 1], [1, -1, 0, 1, 1, -1], [0, 0, 0, 0, 0, 0], [1, 2, 1, 2, 1, -1], [0, 0, 0, 0, -1, 0], [5, -1, 0, 2, -1, 0], [0, 1, 0, -2, 1, 0], [2, -1, 0, 2, -1, -3], [0, 1, 1, 1, 0, -1], [1, 1, 0, 1, 1, -3], [-3, 3, 3, -3, 3, 0], [-1, 1, 0, -1, 8, 1], [0, -4, -3, -4, 0, 3], [-3, 3, 0, 3, -3, 0], [-7, 2, 3, -1, 2, 0], [2, -1, 0, 2, 2, -3], [-1, 1, 3, 1, -1, -3], [-1, 8, 0, -1, 3, -6], [4, -2, -3, 1, -2, 0], [-4, 5, 6, -4, 5, 0], [-3, 5, 6, 5, -3, -6], [-4, -1, 0, -1, -4, 0], [-2, 1, -5, -7, 1, 0], [2, 5, 3, 5, 2, -3], [-3, 1, 4, 1, -3, -4], [2, -1, 0, 2, 9, -3], [5, -4, -4, 4, -4, 0], [-6, -3, -6, 0, -3, 0], [-4, -2, 0, -4, 2, 10], [4, 1, 3, 1, 1, 0], [-4, 3, 0, -4, -4, 5], [8, 2, 3, 2, 8, -3], [1, -2, 0, 1, -2, 0], [-3, 9, 0, -3, 6, -3], [0, 5, 9, 5, 0, -9], [-1, 2, 0, -1, -2, 0], [-1, 1, -6, -8, 1, 0], [-4, 0, 0, -4, 5, 8], [2, -6, -5, -6, 2, 5], [4, -5, -2, 8, -5, 0], [-9, -5, -3, 7, -5, 0], [-6, -2, 1, -2, -6, -1], [0, -9, 0, 0, -10, 9], [4, -2, 5, 9, -2, 0], [9, -6, 3, 15, -6, 0], [6, -6, 0, 6, -5, -6], [-5, -6, 0, -6, -5, 0], [-6, -3, -3, -3, -6, 3], [4, -14, 0, 4, -13, 6], [-9, 3, 9, 3, 3, 0], [-2, 4, 0, -2, 13, 0], [-3, 7, -3, 7, -3, 3], [5, -7, -2, 12, -7, 0], [-2, 0, 0, -2, 10, 4], [-3, -5, -8, -5, -3, 8], [10, 4, 3, -5, 4, 0], [14, -3, -9, -3, -3, 0], [2, 3, 0, 3, 2, 0], [-12, -1, -10, -1, -12, 10], [-7, 11, 0, -7, 1, 3], [0, 11, 0, 0, 12, -11], [7, 5, 0, -10, 5, 0], [-3, -3, 0, -3, 6, 9], [-8, -7, -3, -7, -8, 3], [15, 6, 9, 6, 15, -9], [8, -5, -6, -5, 8, 6], [-8, 13, 0, -8, -4, 3], [3, -8, 0, 3, 12, 2], [10, -6, -6, -6, 10, 6], [-21, 5, 5, 5, -21, -5], [7, 7, 4, -10, 7, 0], [16, -2, 9, -2, 16, -9], [-1, -1, 0, -1, 13, 3], [-2, -2, -9, -5, -2, 0], [1, -5, 0, 1, 1, 3], [-15, 3, 6, 3, -15, -6], [7, -5, -15, -5, -5, 0], [1, -5, 0, 1, -14, 3], [6, -12, 0, 6, 10, 0], [6, -9, 0, 6, -21, -3], [17, 1, 12, 1, 17, -12], [30, 0, 3, 3, 0, 0], [19, 2, 12, 8, 2, 0], [-10, 5, 3, 5, -10, -3], [-10, -10, -12, -10, -10, 12], [3, -3, 0, 6, -3, 0], [9, 7, 6, 7, 9, -6], [22, 11, 10, 11, 22, -10], [2, -1, 0, 2, 15, -3], [1, 7, 3, -11, 7, 0], [17, -3, -2, -3, 17, 2], [6, -4, 3, 11, -4, 0], [-5, -1, 0, -5, 7, 11], [6, -18, 0, 6, -26, 6], [-12, 3, -9, -15, 3, 0], [8, -17, 0, 8, -19, 1], [17, 2, 12, 8, 2, 0], [-26, 2, 3, -1, 2, 0], [-13, 6, 6, -6, 6, 0], [-3, -5, -9, -5, -3, 9], [12, 12, 11, -13, 12, 0], [5, 9, 0, 5, -16, -19], [3, 4, -2, 4, 3, 2], [14, -13, 0, 14, -2, -15], [5, -6, -3, 9, -6, 0], [27, 2, 5, 2, 27, -5], [14, -1, 12, 14, -1, 0], [-4, 2, 0, -4, 20, 6], [7, 10, 9, 10, 7, -9], [-4, -4, 0, -4, 9, 12], [25, 0, 6, 6, 0, 0], [1, 1, 0, 1, -8, -3], [15, 5, 15, 5, 15, -15], [18, 1, 15, 13, 1, 0], [11, -7, 3, -7, 11, -3], [4, -5, 0, 4, 2, -3], [18, -15, -4, 26, -15, 0], [11, -10, 0, 11, -19, -12], [1, 7, 6, 7, 1, -6], [-12, 3, 0, -12, 14, 21], [-1, 12, 15, 12, -1, -15], [10, 7, 9, 7, 10, -9], [2, -10, -24, -4, -10, 0], [-29, -4, 3, -4, -29, -3], [20, -10, -24, -4, -10, 0], [0, 6, 18, 6, 0, -18], [16, -2, -9, -5, -2, 0], [20, 6, 3, 6, 20, -3], [0, 12, 0, 0, -9, -12], [-8, 4, -15, -23, 4, 0], [9, -18, 0, 9, -27, 0], [-11, 16, 0, -11, 20, 6], [-23, -1, 6, 8, -1, 0], [-4, 14, 0, -4, 8, -6], [-14, 7, 0, -14, -1, 21], [1, 4, -10, -18, 4, 0], [7, 7, 0, 7, -9, -21], [-9, 16, 0, -9, -15, 2], [-3, 9, 18, 0, 9, 0], [7, 6, 15, 3, 6, 0], [25, -3, -4, -3, 25, 4], [0, 0, 0, 0, -36, 0], [-32, 10, -3, -23, 10, 0], [-10, 1, 12, 10, 1, 0], [-7, 16, 2, 16, -7, -2], [-19, -9, -18, -9, -19, 18], [-33, -7, -7, -7, -33, 7], [-16, 14, 0, -16, 15, 18], [-9, -3, -18, -12, -3, 0], [3, -12, 0, 3, -23, 6], [-1, -1, 9, 11, -1, 0], [-29, 11, 3, -19, 11, 0], [-4, 13, 0, -4, 35, -5], [-31, -8, -6, -8, -31, 6], [-8, 13, 3, 13, -8, -3], [-12, -11, -21, 1, -11, 0], [4, 5, 19, 5, 4, -19], [-9, -3, 0, 6, -3, 0], [5, 7, 0, 5, 17, -17], [23, 13, 5, 13, 23, -5], [-30, 12, 4, -20, 12, 0], [-9, -12, 0, -9, 1, 30], [7, -5, -18, -8, -5, 0], [-4, 20, 0, -4, -7, -12], [-15, -3, -21, -3, -15, 21], [-10, 3, 6, 0, 3, 0], [-30, -16, -12, -16, -30, 12]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_441_f_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_441_2_f_d();".
// 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_441_2_f_d(:prec:=6)
    chi := MakeCharacter_441_f();
    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_441_2_f_d();".
// 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_441_2_f_d( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_441_f();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![1, -4, 17, 2, 5, -1, 1]>,<5,R![121, -22, 59, 32, 23, 5, 1]>],Snew);
    return Vf;
end function;