
// Make newform 294.3.b.f in Magma, downloaded from the LMFDB on 06 January 2026.
// To make the character of type GrpDrchElt, type "MakeCharacter_294_b();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_294_b_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_294_3_b_f();".
// 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_294_3_b_f();".
// 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, 0, 0, 0, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 1], [0, 1, 0, -1]];
    Rf_basisdens := [1, 1, 1, 1];
    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_294_b();"
function MakeCharacter_294_b()
    N := 294;
    order := 2;
    char_gens := [197, 199];
    v := [1, 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_294_b_Hecke();"
function MakeCharacter_294_b_Hecke( : Kf := false)
    N := 294;
    order := 2;
    char_gens := [197, 199];
    char_values := [[-1, 0, 0, 0], [1, 0, 0, 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 := 3;
    raw_aps := [[0, 0, -1, 0], [0, 3, 0, 0], [0, -8, 0, 0], [0, 0, 0, 0], [0, 0, 5, 0], [0, 0, 0, -15], [0, -20, 0, 0], [0, 0, 0, -4], [0, 0, 13, 0], [0, 0, -20, 0], [0, 0, 0, -36], [-50, 0, 0, 0], [0, -20, 0, 0], [20, 0, 0, 0], [0, 10, 0, 0], [0, 0, 8, 0], [0, -80, 0, 0], [0, 0, 0, 49], [60, 0, 0, 0], [0, 0, 45, 0], [0, 0, 0, 25], [80, 0, 0, 0], [0, -10, 0, 0], [0, 20, 0, 0], [0, 0, 0, 65], [0, 0, 0, 0], [0, 0, 0, -80], [0, 0, -53, 0], [-32, 0, 0, 0], [0, 0, -108, 0], [-80, 0, 0, 0], [0, 150, 0, 0], [0, 0, 12, 0], [0, 0, 0, 44], [0, 0, 80, 0], [-280, 0, 0, 0], [0, 0, 0, -145], [-140, 0, 0, 0], [0, 134, 0, 0], [0, 0, 0, 0], [0, 0, -195, 0], [0, 0, 0, -9], [0, 0, -245, 0], [80, 0, 0, 0], [0, 0, -188, 0], [0, 0, 0, -204], [228, 0, 0, 0], [0, 0, 0, 60], [0, -96, 0, 0], [0, 0, 0, 9], [0, 0, -192, 0], [0, 0, -75, 0], [0, 0, 0, 111], [0, -160, 0, 0], [0, 36, 0, 0], [0, 0, 147, 0], [0, -40, 0, 0], [0, 0, 0, 176], [-320, 0, 0, 0], [0, 0, 80, 0], [0, 0, 0, -320], [0, -64, 0, 0], [0, 0, 0, -140], [0, 410, 0, 0], [0, 0, 0, -345], [0, 0, 8, 0], [388, 0, 0, 0], [-400, 0, 0, 0], [0, 0, -267, 0], [0, 0, 0, -129], [0, 556, 0, 0], [0, 0, 365, 0], [0, 0, 0, -20], [-110, 0, 0, 0], [100, 0, 0, 0], [0, 320, 0, 0], [0, 0, 100, 0], [0, 0, 0, 95], [0, 0, 180, 0], [0, 0, 0, 201], [0, -560, 0, 0], [480, 0, 0, 0], [0, 0, -555, 0], [0, 0, 0, -255], [0, 0, 0, -336], [0, 0, 187, 0], [0, 0, 60, 0], [-510, 0, 0, 0], [0, -520, 0, 0], [640, 0, 0, 0], [0, -416, 0, 0], [0, 310, 0, 0], [-600, 0, 0, 0], [0, 0, 165, 0], [620, 0, 0, 0], [0, 800, 0, 0], [0, -760, 0, 0], [0, -860, 0, 0], [0, 0, 0, -600], [160, 0, 0, 0], [940, 0, 0, 0], [0, 0, 432, 0], [0, -80, 0, 0], [0, 0, 440, 0], [-692, 0, 0, 0], [0, 0, 0, -225], [0, -480, 0, 0], [0, 764, 0, 0], [0, 0, 685, 0], [0, 0, 0, -681], [0, 0, 0, 660], [480, 0, 0, 0], [0, 0, 668, 0], [0, 0, 0, 536], [200, 0, 0, 0], [0, 0, -740, 0], [0, 0, 0, -520], [0, 294, 0, 0], [0, 0, -648, 0], [0, 0, -45, 0], [0, 0, 0, 759], [-930, 0, 0, 0], [0, 696, 0, 0], [0, 0, -357, 0], [0, 0, 0, 36], [0, 0, -120, 0], [-320, 0, 0, 0], [0, -320, 0, 0], [0, 0, 0, 800], [0, 0, 0, -495], [372, 0, 0, 0], [0, 0, -307, 0], [152, 0, 0, 0], [-640, 0, 0, 0], [0, -340, 0, 0], [0, 0, 0, 159], [0, -1240, 0, 0], [0, 0, 0, -620], [0, -1080, 0, 0], [0, 0, -980, 0], [0, 0, 0, 1104], [0, 0, -360, 0], [1360, 0, 0, 0], [0, 0, -843, 0], [0, 0, 0, 319], [0, 550, 0, 0], [0, 0, 0, 105], [0, 1460, 0, 0], [0, 0, 0, -116], [0, 0, 187, 0], [-160, 0, 0, 0], [0, -660, 0, 0], [-340, 0, 0, 0], [0, 1190, 0, 0], [-1340, 0, 0, 0], [0, 0, -245, 0], [88, 0, 0, 0], [0, 1540, 0, 0], [0, 0, 0, -745], [0, -1520, 0, 0], [0, 0, -93, 0], [0, 0, -1168, 0], [-840, 0, 0, 0], [0, 310, 0, 0], [0, 0, -912, 0], [0, 416, 0, 0], [32, 0, 0, 0], [0, 0, 0, 745]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_294_b_Hecke( : Kf := Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_294_3_b_f();".
// 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_294_3_b_f(:prec:=4)
    chi := MakeCharacter_294_b();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 3));
    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_294_3_b_f();".
// 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_294_3_b_f( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_294_b();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,3,sign)));
    Vf := Kernel([<5,R![64, 0, 1]>,<13,R![-450, 0, 1]>],Snew);
    return Vf;
end function;