
// Make newform 210.2.t.b in Magma, downloaded from the LMFDB on 04 September 2025.
// To make the character of type GrpDrchElt, type "MakeCharacter_210_t();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_210_t_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_210_2_t_b();".
// 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_210_2_t_b();".
// 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 := [9, -3, -2, -1, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0], [0, 1, 0, 0], [-3, -2, 2, 1], [3, 2, 0, -1]];
    Rf_basisdens := [1, 1, 6, 2];
    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_210_t();"
function MakeCharacter_210_t()
    N := 210;
    order := 6;
    char_gens := [71, 127, 31];
    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_210_t_Hecke();"
function MakeCharacter_210_t_Hecke( : Kf := false)
    N := 210;
    order := 6;
    char_gens := [71, 127, 31];
    char_values := [[-1, 0, 0, 0], [-1, 0, 0, 0], [1, 0, -1, 0]];
    assert UnitGenerators(DirichletGroup(N)) eq char_gens;
    values := ConvertToHeckeField(char_values : pass_field := ISA(Type(Kf), Fld), 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]];
    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 := [[-1, 0, 1, 0], [0, -1, 0, 0], [0, 0, -2, -1], [2, 0, 1, 0], [3, 0, -1, 1], [2, 0, 0, 0], [0, 0, 2, 4], [-2, 0, -2, 0], [-2, 1, 1, -2], [1, -2, 0, 2], [3, 0, -3, -3], [-2, 6, 4, 0], [5, -1, -1, -1], [5, -3, -7, 3], [-4, 2, -2, 0], [1, -2, 1, 1], [-3, 6, -3, -3], [-6, 3, -3, 0], [-3, 0, 0, -3], [-2, -2, 6, 2], [0, 0, -2, 0], [1, -3, 2, 6], [1, 4, -6, -4], [2, -1, -1, 2], [8, -3, -3, -3], [-1, 2, 14, -1], [-8, 3, 5, -6], [-13, 2, 11, -4], [3, -6, -2, 3], [-10, 2, 2, 2], [0, -3, 3, 3], [7, 1, -8, -2], [2, -4, 2, 2], [4, -6, -2, 6], [2, -7, -5, 0], [-3, 6, 1, -3], [0, 0, -8, 0], [-2, 0, -2, 0], [7, 1, -15, -1], [8, -4, 4, 0], [12, 0, -10, -8], [-9, 3, 15, -3], [8, -4, 4, 0], [-15, 0, 9, 3], [0, -6, -6, -6], [-10, 0, 2, -6], [2, -6, -6, -6], [8, 3, 3, 3], [3, 0, -7, -11], [8, 0, 8, 0], [14, -4, -10, 8], [-2, -8, 12, 8], [-5, 0, 7, 9], [6, 3, 3, 3], [2, 2, 4, 0], [-1, 2, -4, -1], [-8, 16, 1, -8], [1, -9, -8, 0], [22, 0, -8, 6], [-8, 10, 6, -10], [0, 0, 16, 0], [-14, 1, 27, -1], [17, -3, -3, -3], [6, -12, 0, 6], [7, -3, -4, 6], [-9, 3, 6, -6], [4, 6, -10, -12], [4, -3, -5, 3], [3, -6, -12, 3], [-7, 15, -1, -15], [-18, 0, 8, -2], [14, -4, 10, 0], [-6, 12, 7, -6], [8, -12, -4, 0], [2, 6, 6, 6], [-4, 11, 7, 0], [-24, 0, 8, -8], [-8, 0, 8, 0], [-10, -1, -11, 0], [-18, 0, 3, -12], [-16, -4, -4, -4], [5, 3, 3, 3], [-12, 0, 8, 4], [-34, 0, 0, 0], [-3, -3, -6, 0], [-9, 0, 9, 0], [13, -17, -9, 17], [3, 3, 6, 0], [-14, 4, 4, 4], [-17, 9, 25, -9], [-16, 11, -5, 0], [2, -4, -4, 2], [11, 0, -7, -3], [16, 1, -33, -1], [-14, 6, 8, -12], [-5, 1, 9, -1], [-5, -2, 7, 4], [-2, 4, -8, -2], [10, -6, -4, 12], [-8, -9, 17, 18], [-1, -3, 5, 3], [-5, 10, -11, -5], [6, 0, -1, 4], [2, -10, -8, 0], [6, -12, -20, 6], [3, -6, 25, 3], [16, -11, -21, 11], [14, -4, 10, 0], [-6, 0, 2, -2], [2, -9, 5, 9], [1, 12, -13, -24], [8, 0, -10, -12], [-28, 8, 8, 8], [4, 0, 4, 12], [20, 3, 3, 3], [3, 0, 2, 7], [-4, 6, 6, 6], [39, 0, -22, -5], [13, 1, -14, -2], [-14, 16, 12, -16], [9, 0, -6, -3], [14, 9, -37, -9], [-7, -13, -20, 0], [-8, 16, -5, -8], [0, -12, -12, 0], [-11, -8, 30, 8], [-2, -3, 5, 6], [38, 2, -40, -4], [-19, 0, 0, 0], [-8, 12, -4, -24], [-6, 12, 22, -6], [5, -7, -7, -7], [-35, 3, 32, -6], [6, 6, -18, -6], [34, -8, -26, 16], [22, -3, -41, 3], [6, 0, -4, -2], [3, -6, -20, 3], [-2, 1, 3, -1], [39, 0, -22, -5], [6, 0, -12, 0], [5, 5, 10, 0], [33, 0, -12, 9], [33, 0, 0, 0], [-10, 0, 2, -6], [-32, 10, 10, 10], [-10, 12, 12, 12], [36, 0, -16, 4], [-16, 24, 8, 0], [-10, -1, 11, 2], [8, -18, -10, 0], [-21, -9, -9, -9], [-18, 30, 6, -30], [-4, -19, -23, 0], [-23, 0, 4, -15], [16, 4, -36, -4], [4, -6, 2, 12], [-24, -3, 27, 6], [20, 9, 9, 9], [-9, 18, 3, -9], [-36, 3, 33, -6], [-48, 0, 0, 0], [19, -24, -14, 24], [-31, -1, 32, 2], [-12, 24, 12, -12], [-27, 0, 14, 1], [-9, 18, 7, -9], [12, -24, -2, 12]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_210_t_Hecke( : Kf := Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_210_2_t_b();".
// 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_210_2_t_b(:prec:=4)
    chi := MakeCharacter_210_t();
    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_210_2_t_b();".
// 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_210_2_t_b( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_210_t();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<11,R![16, -36, 31, -9, 1]>,<13,R![-2, 1]>,<23,R![36, -18, 15, 3, 1]>],Snew);
    return Vf;
end function;