
// Make newform 693.2.i.g in Magma, downloaded from the LMFDB on 10 November 2025.
// To make the character of type GrpDrchElt, type "MakeCharacter_693_i();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_693_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_693_2_i_g();".
// 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_693_2_i_g();".
// 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, -12, 19, -2, 5, -1, 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], [-60, 12, -19, 25, -5, 1], [-240, 48, -76, 17, -20, 4], [204, -323, -35, -85, 17, -20], [-36, -275, -28, -68, -3, -16]];
    Rf_basisdens := [1, 1, 83, 83, 249, 83];
    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_693_i();"
function MakeCharacter_693_i()
    N := 693;
    order := 3;
    char_gens := [155, 199, 442];
    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_693_i_Hecke();"
function MakeCharacter_693_i_Hecke( : Kf := false)
    N := 693;
    order := 3;
    char_gens := [155, 199, 442];
    char_values := [[1, 0, 0, 0, 0, 0], [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 := 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 := [[0, 0, 0, 1, 0, -1], [0, 0, 0, 0, 0, 0], [0, -1, -1, -1, -1, 1], [1, -1, 0, 1, -1, -1], [-1, 0, 0, 0, 1, 0], [-4, 0, -1, 0, 0, 0], [-1, 0, 0, 0, 1, -1], [0, -2, -2, -1, 3, 1], [0, 0, 0, -1, 4, 1], [2, 0, -3, 1, 0, 0], [2, -3, 0, 0, -2, -1], [0, 2, 2, -2, 2, 2], [2, 0, 1, -4, 0, 0], [1, 0, 1, -2, 0, 0], [0, 0, 0, -1, -1, 1], [6, -1, 0, 0, -6, 2], [3, -1, 0, 0, -3, 6], [0, 0, 0, -2, 8, 2], [6, -2, 0, 0, -6, 0], [-1, 0, 4, 3, 0, 0], [5, 5, 0, 0, -5, 0], [0, 3, 3, 1, 0, -1], [3, 0, -2, 1, 0, 0], [0, -1, -1, -1, 0, 1], [4, 0, 3, 0, 0, 0], [0, -2, 0, 0, 0, -3], [0, 2, 2, -1, 0, 1], [0, -3, -3, 3, -1, -3], [11, -1, 0, 0, -11, 3], [1, 0, -6, -3, 0, 0], [-1, 0, -5, 6, 0, 0], [0, 1, 1, -3, -6, 3], [-3, 3, 0, 0, 3, 2], [-7, 0, -2, 0, 0, 0], [0, 0, 0, 0, -1, 0], [-12, 3, 0, 0, 12, 2], [5, -2, 0, 0, -5, 4], [0, 0, 0, 6, 5, -6], [8, 0, 5, 1, 0, 0], [0, 5, 5, 0, 10, 0], [-5, -5, 0, 0, 5, -2], [-7, 0, 1, -8, 0, 0], [0, 4, 4, -4, 5, 4], [-8, 7, 0, 0, 8, -6], [6, 0, 8, 5, 0, 0], [2, 5, 0, 0, -2, 3], [-2, 0, 6, 4, 0, 0], [13, 0, 0, 4, 0, 0], [1, 7, 0, 0, -1, -5], [0, 2, 2, -8, 7, 8], [0, -4, -4, -4, -9, 4], [8, 0, 5, 7, 0, 0], [9, -5, 0, 0, -9, 2], [-15, 0, -2, -5, 0, 0], [0, 9, 9, 9, 6, -9], [-6, 6, 0, 0, 6, 3], [-6, -3, 0, 0, 6, 3], [0, 4, 4, 12, 5, -12], [3, -11, 0, 0, -3, 4], [-17, 0, 1, -1, 0, 0], [0, -6, 0, 0, 0, 7], [-9, 0, -4, 2, 0, 0], [-1, 0, -5, -9, 0, 0], [23, -1, 0, 0, -23, -5], [0, -8, -8, 9, -7, -9], [0, -1, -1, -4, 9, 4], [0, -6, -6, -10, -1, 10], [15, 0, 8, -5, 0, 0], [-10, 5, 0, 0, 10, -1], [-7, 0, -4, 4, 0, 0], [0, 7, 0, 0, 0, 4], [0, 12, 12, -1, 2, 1], [2, 5, 0, 0, -2, -5], [0, 14, 14, 8, 1, -8], [-11, 0, -4, -5, 0, 0], [0, 9, 9, 8, 14, -8], [12, -7, 0, 0, -12, -9], [0, -6, -6, 2, 18, -2], [0, -7, -7, 6, -15, -6], [14, 3, 0, 0, -14, -9], [-13, 0, 4, -6, 0, 0], [-14, 0, -10, -9, 0, 0], [-5, -2, 0, 0, 5, -4], [2, 0, 6, -8, 0, 0], [0, -2, -2, 5, -4, -5], [0, -1, -1, 1, 15, -1], [-15, 0, 0, -10, 0, 0], [0, 4, 4, 1, -5, -1], [15, 0, 10, -3, 0, 0], [-2, 0, 1, 9, 0, 0], [0, -8, -8, 5, 6, -5], [8, -1, 0, 0, -8, 11], [-5, -1, 0, 0, 5, -4], [-9, 0, -12, 12, 0, 0], [0, -7, -7, 7, -2, -7], [-12, 0, -7, -4, 0, 0], [0, -2, -2, 9, -4, -9], [10, 2, 0, 0, -10, -7], [0, 0, 0, 3, 7, -3], [0, -7, -7, 5, -8, -5], [-3, 0, 10, 10, 0, 0], [23, -7, 0, 0, -23, 3], [-19, 15, 0, 0, 19, 9], [0, 6, 6, 1, -24, -1], [5, 14, 0, 0, -5, 3], [-23, 4, 0, 0, 23, 3], [15, 0, -7, -4, 0, 0], [0, -3, -3, 3, 18, -3], [-3, 13, 0, 0, 3, 2], [-25, 0, 5, 5, 0, 0], [0, 1, 1, -12, -8, 12], [-16, -8, 0, 0, 16, -6], [24, 0, 4, -8, 0, 0], [-8, -2, 0, 0, 8, -16], [-9, 0, -9, -6, 0, 0], [-24, -1, 0, 0, 24, 9], [4, 0, -4, 2, 0, 0], [6, -4, 0, 0, -6, 2], [0, 3, 3, -4, -26, 4], [8, 0, -2, -3, 0, 0], [25, 11, 0, 0, -25, -5], [16, 0, -12, -6, 0, 0], [0, 22, 22, 7, -1, -7], [6, -3, 0, 0, -6, -8], [0, -12, -12, 0, 12, 0], [3, 0, 2, -9, 0, 0], [0, -9, -9, -23, -12, 23], [0, -13, -13, 1, 19, -1], [26, 0, 15, -7, 0, 0], [0, 6, 6, 7, 31, -7], [-9, 13, 0, 0, 9, -20], [0, 0, 1, 5, 0, 0], [0, -3, -3, 5, -31, -5], [-1, 0, 17, 13, 0, 0], [0, -4, -4, -9, 6, 9], [25, 0, 18, -12, 0, 0], [3, 10, 0, 0, -3, 1], [-2, 7, 0, 0, 2, -10], [-14, 0, -16, 3, 0, 0], [3, -6, 0, 0, -3, -16], [-25, 0, -7, -13, 0, 0], [0, -27, -27, -3, 3, 3], [-2, 5, 0, 0, 2, 17], [16, 0, 3, -2, 0, 0], [29, 3, 0, 0, -29, 0], [15, 0, -3, 11, 0, 0], [8, 0, -14, 6, 0, 0], [20, 10, 0, 0, -20, -9], [0, 21, 21, 12, 8, -12], [0, -7, -7, 9, -29, -9], [0, 3, 3, 12, -7, -12], [12, 0, 11, -16, 0, 0], [-44, 0, -1, -8, 0, 0], [0, 2, 2, -17, 1, 17], [7, -2, 0, 0, -7, -6], [9, 0, 13, 11, 0, 0], [0, 0, 0, 4, 9, -4], [0, 3, 3, -3, 21, 3], [6, 0, -7, 13, 0, 0], [7, -3, 0, 0, -7, -4], [0, -13, -13, -7, 5, 7], [-14, 0, 12, 11, 0, 0], [-19, 0, 5, 12, 0, 0], [0, -2, -2, -11, 2, 11], [8, 6, 0, 0, -8, -5], [3, -15, 0, 0, -3, -8], [5, 4, 0, 0, -5, 5], [6, 5, 0, 0, -6, -10]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_693_i_Hecke( : Kf := Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_693_2_i_g();".
// 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_693_2_i_g(:prec:=6)
    chi := MakeCharacter_693_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_693_2_i_g();".
// 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_693_2_i_g( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_693_i();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![9, -15, 25, -6, 5, 0, 1]>,<5,R![25, 35, 59, -4, 11, 2, 1]>],Snew);
    return Vf;
end function;