
// Make newform 273.2.i.e in Magma, downloaded from the LMFDB on 19 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_273_i();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_273_i_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_273_2_i_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_273_2_i_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 := [4, -4, 18, -10, 59, -40, 41, -8, 7, -1, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0, 0, 0, 0, 0], [66894, 615246, 240781, 65127, 368907, 75479, 63880, 15246, 11641, 2640], [10560, -77454, -668815, -267181, 90633, -474507, 32761, -85000, 3234, -14281], [-56648, 240426, -652973, 781623, -573725, 394774, -107661, 66934, -12294, 8527], [309726, 559102, 1092753, 386739, 485035, 622413, 67797, 119172, 15246, 19323], [-309726, -154746, -1092753, -386739, -485035, -622413, -67797, -119172, -15246, -19323], [-53822, -70588, 272268, -954458, 872266, -728569, 176861, -123529, 22689, -18327], [30728, -215730, -857529, -741539, 268553, -1251855, 91577, -225894, 4356, -37803], [227351, -77056, 297216, -989025, 952192, -795328, 190701, -134848, 24768, -20287], [-173616, 785430, -415643, 2576313, -1734081, 1832021, -348849, 313068, -43061, 45021]];
    Rf_basisdens := [1, 101089, 202178, 101089, 202178, 202178, 101089, 202178, 101089, 101089];
    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_273_i();"
function MakeCharacter_273_i()
    N := 273;
    order := 3;
    char_gens := [92, 157, 106];
    v := [3, 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_273_i_Hecke();"
function MakeCharacter_273_i_Hecke(Kf)
    N := 273;
    order := 3;
    char_gens := [92, 157, 106];
    char_values := [[1, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, -1, 0, 0, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 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, 0, 0, 0, 1, 0, 0, 0, -1, 0], [1, 0, -1, 0, 0, 0, 0, 0, 0, 0], [0, 0, 1, 0, 0, 0, 0, 1, 0, 0], [0, 0, 0, 0, -1, 0, -1, 0, 1, 0], [0, 1, 0, 0, 1, 0, 0, 0, 0, 0], [-1, 0, 0, 0, 0, 0, 0, 0, 0, 0], [3, 0, -3, 1, 0, 0, 1, 0, 0, 0], [0, 0, 1, 0, -1, 0, 0, -1, 1, 0], [0, 0, 0, 1, 0, 0, 0, 0, 0, -2], [-2, 0, 0, 0, 0, -1, 0, 1, 2, 0], [1, 1, -1, 1, -2, 1, 1, 0, 0, 0], [0, 0, -4, 2, 0, 0, 0, -2, 0, -1], [-1, -1, 0, 0, 0, -1, 1, 1, -2, 1], [2, 2, 0, 0, 0, 0, 1, 0, -2, -2], [0, 0, -1, 1, -1, 0, 0, -1, 1, 3], [0, 3, 0, 0, 2, 3, 0, 0, 0, 0], [4, -3, -4, 3, -3, -2, 3, 0, 0, 0], [0, 0, 5, -1, 0, 0, 0, 0, 0, 0], [-4, -1, 4, 2, 1, 0, 2, 0, 0, 0], [-6, 1, 0, 0, 0, 2, 1, -2, -1, -1], [3, -1, -3, -1, 2, 1, -1, 0, 0, 0], [0, 0, -1, 1, -2, 0, 0, 3, 2, -1], [-1, -1, 0, 0, 0, 1, 4, -1, -2, 1], [0, 0, 5, 1, 0, 0, 0, -1, 0, 0], [-2, -3, 0, 0, 0, -2, -2, 2, 4, 3], [-3, -2, 3, -6, 2, -1, -6, 0, 0, 0], [0, 0, 2, -1, -4, 0, 0, 0, 4, 5], [0, 0, 4, -5, 4, 0, 0, 2, -4, 4], [3, -2, -3, 3, 2, 1, 3, 0, 0, 0], [-7, -1, 0, 0, 0, 0, 0, 0, -2, 1], [-3, -2, 0, 0, 0, 1, -5, -1, 2, 2], [0, 0, 4, -2, 2, 0, 0, -2, -2, -5], [-2, 0, 2, -5, 2, -2, -5, 0, 0, 0], [-1, 3, 0, 0, 0, 3, 1, -3, 6, -3], [0, 0, -6, 2, 2, 0, 0, -2, -2, 0], [-3, -3, 3, -5, 3, -1, -5, 0, 0, 0], [4, -1, -4, 7, -2, -1, 7, 0, 0, 0], [0, 0, -12, -1, 5, 0, 0, 2, -5, -1], [5, -2, 0, 0, 0, -1, 4, 1, -3, 2], [0, 0, 1, 4, -2, 0, 0, 2, 2, 0], [7, -3, -7, -2, -6, -1, -2, 0, 0, 0], [-2, -4, 0, 0, 0, 1, 3, -1, 0, 4], [0, 0, -3, -6, -2, 0, 0, -1, 2, 0], [1, 4, -1, 1, -4, 1, 1, 0, 0, 0], [3, 5, 0, 0, 0, 1, -1, -1, -6, -5], [-11, 1, 11, -4, 0, 3, -4, 0, 0, 0], [6, -5, 0, 0, 0, -2, 3, 2, 2, 5], [-6, -4, 0, 0, 0, 0, 0, 0, 3, 4], [-2, 2, 2, 4, -6, 4, 4, 0, 0, 0], [0, 0, 4, -1, 2, 0, 0, 4, -2, 1], [0, 0, 1, -1, 2, 0, 0, 2, -2, -2], [-3, 6, 0, 0, 0, 3, 1, -3, -1, -6], [13, 2, -13, -2, -2, -3, -2, 0, 0, 0], [-9, 0, 0, 0, 0, -1, 4, 1, 0, 0], [0, 0, -3, -6, 8, 0, 0, 1, -8, 1], [14, -3, -14, 0, 0, -4, 0, 0, 0, 0], [8, -1, -8, 0, 8, 3, 0, 0, 0, 0], [0, 0, 8, -3, 1, 0, 0, -2, -1, -6], [5, -5, -5, 0, -2, -8, 0, 0, 0, 0], [-6, 2, 0, 0, 0, 4, -5, -4, 0, -2], [-11, 4, 11, 1, -6, -3, 1, 0, 0, 0], [13, 1, 0, 0, 0, -1, 1, 1, -6, -1], [3, -6, 0, 0, 0, -5, 3, 5, -3, 6], [-3, 5, 3, -4, -6, 3, -4, 0, 0, 0], [0, 0, -8, 1, -4, 0, 0, 4, 4, 4], [0, 0, 8, 0, -6, 0, 0, -2, 6, 9], [0, 0, -15, 1, 0, 0, 0, 3, 0, -2], [4, 1, 0, 0, 0, 1, 5, -1, 2, -1], [7, 4, -7, 1, 0, -1, 1, 0, 0, 0], [-7, 6, 0, 0, 0, 3, -7, -3, 0, -6], [11, -7, -11, 3, 0, -5, 3, 0, 0, 0], [0, 0, 5, 1, 0, 0, 0, 3, 0, 6], [-1, 4, 1, -6, 8, -1, -6, 0, 0, 0], [0, 0, -3, 2, -2, 0, 0, -2, 2, -8], [10, -7, 0, 0, 0, 0, 4, 0, -4, 7], [0, 0, 4, 3, -6, 0, 0, 4, 6, 2], [16, -6, -16, 1, 10, -1, 1, 0, 0, 0], [0, 0, -9, 2, 0, 0, 0, 5, 0, 6], [0, 0, 6, 3, 8, 0, 0, 0, -8, -3], [2, 0, -2, 3, 10, 2, 3, 0, 0, 0], [-8, 3, 0, 0, 0, -2, -1, 2, -4, -3], [6, -3, 0, 0, 0, -4, -3, 4, -8, 3], [9, -5, -9, 1, 2, 1, 1, 0, 0, 0], [-11, 1, 0, 0, 0, -4, 0, 4, 2, -1], [0, 0, -5, 6, -4, 0, 0, -5, 4, -5], [0, 0, 11, 10, -10, 0, 0, -1, 10, -1], [-11, -1, 0, 0, 0, 1, -4, -1, 0, 1], [0, 0, 5, -4, -4, 0, 0, 3, 4, 10], [17, -5, 0, 0, 0, -3, 2, 3, 8, 5], [0, 1, 0, 0, 0, 6, 2, -6, 8, -1], [0, 0, 1, 6, -10, 0, 0, -3, 10, -4], [-13, -6, 13, 5, -1, 1, 5, 0, 0, 0], [-7, 4, 7, 2, -5, -1, 2, 0, 0, 0], [7, 3, 0, 0, 0, -1, 8, 1, 2, -3], [0, 0, 12, -2, 2, 0, 0, -2, -2, 6], [6, -3, 0, 0, 0, 2, -2, -2, -6, 3], [0, 0, 12, 3, -6, 0, 0, -2, 6, 3], [8, 5, -8, -4, -6, -6, -4, 0, 0, 0], [0, 0, 2, 0, -6, 0, 0, -2, 6, -4], [0, 0, 6, -1, 0, 0, 0, -2, 0, -7], [-9, 6, 0, 0, 0, 3, -5, -3, 10, -6], [4, 3, -4, 7, -2, 0, 7, 0, 0, 0], [-11, 5, 11, 2, 0, 9, 2, 0, 0, 0], [0, 0, 14, -9, 2, 0, 0, 5, -2, -3], [-5, -6, 5, 2, -2, -1, 2, 0, 0, 0], [7, -1, -7, 6, 8, -3, 6, 0, 0, 0], [-6, 3, 0, 0, 0, 4, 2, -4, 9, -3], [0, 0, 9, 6, 4, 0, 0, -3, -4, 2], [19, -5, -19, 1, 14, -1, 1, 0, 0, 0], [-1, -3, 0, 0, 0, 6, 5, -6, -4, 3], [0, 0, 2, -3, 16, 0, 0, -2, -16, -4], [-10, 4, 10, 3, -12, 0, 3, 0, 0, 0], [3, -5, 0, 0, 0, -5, 9, 5, -4, 5], [-1, 1, 1, 7, 2, 7, 7, 0, 0, 0], [-6, 8, 0, 0, 0, -2, -5, 2, 6, -8], [14, -1, -14, -2, 10, 4, -2, 0, 0, 0], [5, 2, 0, 0, 0, 3, 1, -3, -1, -2], [-21, 3, 21, -3, 10, -3, -3, 0, 0, 0], [0, 0, 7, -5, 4, 0, 0, 1, -4, -1], [2, 4, 0, 0, 0, 0, -8, 0, -10, -4], [8, 8, -8, 2, -10, 2, 2, 0, 0, 0], [4, 5, 0, 0, 0, 0, 11, 0, 2, -5], [0, 0, -6, 2, -2, 0, 0, 3, 2, -7], [-2, 1, 2, 2, -4, 4, 2, 0, 0, 0], [0, 0, -7, 9, -5, 0, 0, 7, 5, 0], [2, -12, 0, 0, 0, 0, 0, 0, -4, 12], [0, 0, 11, -7, 6, 0, 0, -5, -6, 1], [0, 0, 10, -2, 12, 0, 0, -6, -12, -3], [13, 2, 0, 0, 0, -7, -12, 7, -2, -2], [0, 0, 2, -3, 4, 0, 0, -4, -4, -9], [-17, 2, 17, -2, 0, 1, -2, 0, 0, 0], [1, 2, 0, 0, 0, -1, -9, 1, 7, -2], [0, 0, 10, 5, 6, 0, 0, 8, -6, 5], [1, 5, 0, 0, 0, -6, 3, 6, -2, -5], [0, 0, 4, -10, 14, 0, 0, -8, -14, -3], [-14, 6, 0, 0, 0, 4, -1, -4, 2, -6], [-1, -3, 1, -3, 0, -1, -3, 0, 0, 0], [11, -1, -11, -4, 9, -5, -4, 0, 0, 0], [2, 4, 0, 0, 0, -6, -5, 6, 4, -4], [-2, -2, 2, -4, -18, -5, -4, 0, 0, 0], [-3, 10, 0, 0, 0, 5, -5, -5, 12, -10], [0, 0, 0, -8, 4, 0, 0, 2, -4, -9], [22, 9, -22, -6, -4, 0, -6, 0, 0, 0], [-12, 2, 0, 0, 0, -4, -1, 4, 13, -2], [8, -3, -8, 0, -4, -1, 0, 0, 0, 0], [-1, -11, 0, 0, 0, 5, -3, -5, -1, 11], [-7, 2, 0, 0, 0, 9, 8, -9, -8, -2], [9, -3, -9, -8, 12, -4, -8, 0, 0, 0], [0, 0, -1, 7, -14, 0, 0, 3, 14, 6], [0, 0, 14, -9, 0, 0, 0, -2, 0, 5], [0, 0, -5, -2, -14, 0, 0, -1, 14, 5], [-16, 6, 0, 0, 0, -4, 5, 4, -8, -6], [3, 2, 0, 0, 0, -1, 3, 1, 0, -2], [0, 0, 17, -4, -4, 0, 0, 3, 4, 0], [-22, 4, 22, 1, -12, 14, 1, 0, 0, 0], [1, 0, 0, 0, 0, -7, -8, 7, -4, 0], [0, 0, -25, -2, 8, 0, 0, 5, -8, -2], [0, 0, 24, -3, 6, 0, 0, -4, -6, 3], [-8, 7, 0, 0, 0, 11, 3, -11, -8, -7], [3, 0, -3, 4, -6, 11, 4, 0, 0, 0], [0, 0, -13, -2, -9, 0, 0, -3, 9, -4], [-17, -1, 0, 0, 0, 2, -5, -2, 4, 1], [-23, 1, 0, 0, 0, 3, -15, -3, 7, -1], [0, 0, -2, 1, -4, 0, 0, -2, 4, 7], [11, 2, -11, 2, -6, 1, 2, 0, 0, 0], [-20, -2, 20, 6, -3, 2, 6, 0, 0, 0], [-6, 6, 6, 8, 0, 10, 8, 0, 0, 0], [-2, -3, 2, -9, -4, 5, -9, 0, 0, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_273_i_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_273_2_i_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_273_2_i_e(:prec:=10)
    chi := MakeCharacter_273_i();
    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_273_2_i_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_273_2_i_e( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_273_i();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![1, 13, 168, 29, 105, -7, 51, -2, 8, 0, 1]>],Snew);
    return Vf;
end function;