
// Make newform 1680.2.ba.a in Magma, downloaded from the LMFDB on 25 September 2025.
// To make the character of type GrpDrchElt, type "MakeCharacter_1680_ba();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_1680_ba_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_1680_2_ba_a();".
// 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_1680_2_ba_a();".
// 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 := [81, -54, 9, 18, -20, 6, 1, -2, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0, 0, 0], [-27, 36, -15, -2, 9, -5, 1, 1], [12, -1, -3, 2, -1, -1, 0, 0], [-54, 36, -12, -7, 9, -4, -1, -1], [54, -9, -18, 20, -6, -1, 2, -1], [-27, 9, 9, -11, 6, 1, -2, 1], [45, -18, 11, 14, -7, 1, 1, -1]];
    Rf_basisdens := [1, 1, 54, 6, 54, 27, 18, 18];
    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_1680_ba();"
function MakeCharacter_1680_ba()
    N := 1680;
    order := 2;
    char_gens := [1471, 421, 1121, 337, 241];
    v := [1, 2, 1, 2, 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_1680_ba_Hecke();"
function MakeCharacter_1680_ba_Hecke( : Kf := false)
    N := 1680;
    order := 2;
    char_gens := [1471, 421, 1121, 337, 241];
    char_values := [[-1, 0, 0, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0, 0, 0], [-1, 0, 0, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0, 0, 0], [1, 0, 0, 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, 0, 0, 0, 0, 0], [0, 0, 0, 0, 1, 0, 0, 0], [0, 0, 1, 0, 0, 0, 0, 0], [0, 0, -1, 0, 0, 0, 0, 0], [-1, 0, 0, 0, -1, 0, -1, -1], [-1, 1, 0, 0, 2, 1, 2, 1], [0, 0, -2, 0, -1, 0, 1, 0], [0, -1, 0, 1, -1, 1, 1, 0], [0, 0, 0, 0, 0, 0, 0, -2], [0, 1, -2, 2, -2, -1, 2, 0], [0, -1, 0, -1, 1, 1, -1, 0], [2, -2, 0, 0, 2, -2, 2, 0], [0, 0, 0, -2, 0, 0, 0, 0], [0, 0, 2, -2, 0, 0, 0, 0], [-6, 2, 0, 0, 1, 2, 1, 0], [0, -1, 0, -1, -3, 1, 3, 0], [0, -2, 0, 0, -2, -2, -2, 0], [0, 0, 0, 0, 2, 0, 2, -2], [0, 2, 8, 0, 2, -2, -2, 0], [-7, 3, 0, 0, 3, 3, 3, 1], [3, 1, 0, 0, 1, 1, 1, -1], [0, -1, -2, 2, -2, 1, 2, 0], [-8, 0, 0, 0, 2, 0, 2, 4], [0, 4, 2, 0, 2, -4, -2, 0], [-7, -1, 0, 0, 0, -1, 0, -1], [0, -2, 4, 2, -4, 2, 4, 0], [0, -2, 4, -2, 1, 2, -1, 0], [0, -2, 0, 0, 2, -2, 2, 2], [-2, 3, 0, 0, 4, 3, 4, 2], [0, 3, -4, 5, -1, -3, 1, 0], [0, 4, -2, 2, -2, -4, 2, 0], [-2, -4, 0, 0, -2, -4, -2, 2], [0, -3, 0, 3, -1, 3, 1, 0], [0, 1, 0, 1, -3, -1, 3, 0], [0, 0, -4, -4, -4, 0, 4, 0], [0, -3, -6, -6, -2, 3, 2, 0], [5, -5, 0, 0, -1, -5, -1, 1], [0, -2, 6, -6, 2, 2, -2, 0], [-4, 0, 0, 0, -5, 0, -5, -4], [0, 4, 10, -4, 1, -4, -1, 0], [-5, 5, 0, 0, 1, 5, 1, 3], [-6, 0, 0, 0, 2, 0, 2, 0], [-15, -2, 0, 0, 1, -2, 1, 1], [4, 0, 0, 0, -6, 0, -6, -6], [0, -5, -8, 3, -3, 5, 3, 0], [0, -5, -4, 3, 1, 5, -1, 0], [0, 5, -6, 4, 0, -5, 0, 0], [0, 8, -8, 4, 3, -8, -3, 0], [-10, -6, 0, 0, -1, -6, -1, 0], [-8, 6, 0, 0, 4, 6, 4, 2], [0, 1, -8, -1, 7, -1, -7, 0], [-3, 2, 0, 0, -7, 2, -7, -3], [-4, 2, 0, 0, -2, 2, -2, 2], [4, 6, 0, 0, 0, 6, 0, -4], [0, -4, 6, 0, 4, 4, -4, 0], [-14, 4, 0, 0, 4, 4, 4, 0], [0, 8, 0, 6, 2, -8, -2, 0], [0, -1, -12, -3, 1, 1, -1, 0], [-4, -8, 0, 0, 0, -8, 0, 2], [0, 1, -2, 2, 6, -1, -6, 0], [0, -8, 0, 0, -3, 8, 3, 0], [0, 6, -2, 2, 1, -6, -1, 0], [0, -2, 8, -6, -1, 2, 1, 0], [2, -6, 0, 0, 4, -6, 4, -2], [5, -5, 0, 0, -4, -5, -4, 7], [0, -5, -8, -1, 3, 5, -3, 0], [0, -6, -16, 4, -4, 6, 4, 0], [0, -4, 0, 0, -4, -4, -4, -2], [2, 10, 0, 0, 2, 10, 2, -4], [0, 4, 0, 0, -8, 4, -8, -6], [0, -6, 6, -6, 1, 6, -1, 0], [-11, -5, 0, 0, -1, -5, -1, 1], [0, -12, 8, -4, -3, 12, 3, 0], [-6, 6, 0, 0, 0, 6, 0, -4], [0, 4, 0, -2, 10, -4, -10, 0], [-2, -2, 0, 0, -6, -2, -6, 4], [0, 9, 6, 0, 4, -9, -4, 0], [-1, -3, 0, 0, -4, -3, -4, -7], [0, 7, -14, 4, 0, -7, 0, 0], [-10, 2, 0, 0, -6, 2, -6, 0], [4, 2, 0, 0, 10, 2, 10, 4], [8, 1, 0, 0, 0, 1, 0, -6], [-5, -2, 0, 0, -5, -2, -5, -1], [-13, 1, 0, 0, 1, 1, 1, 7], [0, 5, 12, 1, -3, -5, 3, 0], [-2, -4, 0, 0, -8, -4, -8, -4], [0, 1, -10, -4, 0, -1, 0, 0], [2, -8, 0, 0, -6, -8, -6, 4], [0, 0, -18, 4, 2, 0, -2, 0], [0, 6, -2, 2, -8, -6, 8, 0], [10, -6, 0, 0, 3, -6, 3, 4], [-14, -8, 0, 0, 2, -8, 2, 6], [0, 6, 6, 6, -2, -6, 2, 0], [15, 0, 0, 0, -1, 0, -1, 3], [0, -1, 18, -2, 2, 1, -2, 0], [4, 4, 0, 0, -5, 4, -5, 0], [0, -4, 12, -2, 2, 4, -2, 0], [0, 14, 8, 2, 8, -14, -8, 0], [0, -4, 0, 8, 0, 4, 0, 0], [4, -7, 0, 0, -4, -7, -4, 6], [0, -4, 20, -4, -4, 4, 4, 0], [0, -3, 20, -9, 3, 3, -3, 0], [18, -6, 0, 0, 6, -6, 6, 0], [0, 4, -12, 4, 4, -4, -4, 0], [0, 10, -24, 4, -4, -10, 4, 0], [7, 1, 0, 0, 6, 1, 6, 1], [-6, 2, 0, 0, -6, 2, -6, -4], [0, 2, 26, 6, -3, -2, 3, 0], [17, 0, 0, 0, 1, 0, 1, 1], [0, 8, 0, 0, 4, 8, 4, -2], [0, 0, 20, 0, -1, 0, 1, 0], [4, 6, 0, 0, -2, 6, -2, -14], [0, -3, -8, -9, 1, 3, -1, 0], [0, -9, 16, -13, 7, 9, -7, 0], [0, 5, -14, -2, -6, -5, 6, 0], [0, 6, 20, 2, -2, -6, 2, 0], [0, -6, 12, -6, 3, 6, -3, 0], [14, -10, 0, 0, -6, -10, -6, -8], [0, -1, -28, 3, -5, 1, 5, 0], [-15, 6, 0, 0, -11, 6, -11, -3], [4, -4, 0, 0, 10, -4, 10, 6], [-6, -6, 0, 0, 8, -6, 8, 4], [0, -14, 2, -2, -9, 14, 9, 0], [30, 2, 0, 0, 0, 2, 0, 0], [0, -5, -20, 1, 1, 5, -1, 0], [0, -13, 6, -6, -2, 13, 2, 0], [-12, -1, 0, 0, 8, -1, 8, 6], [-12, 10, 0, 0, 12, 10, 12, -4], [0, 2, 0, 10, -2, -2, 2, 0], [1, -5, 0, 0, -2, -5, -2, 15], [0, 7, -18, 0, 4, -7, -4, 0], [2, 8, 0, 0, 14, 8, 14, 4], [0, -7, -18, 0, 4, 7, -4, 0], [-16, 0, 0, 0, 10, 0, 10, -2], [0, -6, -10, 4, -10, 6, 10, 0], [12, -8, 0, 0, 0, -8, 0, 2], [0, 8, 10, 4, 1, -8, -1, 0], [0, 2, 4, 6, -1, -2, 1, 0], [0, 4, -14, 12, -5, -4, 5, 0], [0, -3, 6, 2, -10, 3, 10, 0], [0, 5, -24, 9, 1, -5, -1, 0], [0, -1, -22, -6, -6, 1, 6, 0], [0, -8, -10, -6, -6, 8, 6, 0], [36, 0, 0, 0, 4, 0, 4, -2], [-14, 0, 0, 0, -6, 0, -6, -4], [-10, 4, 0, 0, 10, 4, 10, 2], [17, 3, 0, 0, 7, 3, 7, 1], [0, -2, 14, -2, -2, 2, 2, 0], [0, -13, -8, -7, -11, 13, 11, 0], [0, -6, 0, 0, 0, -6, 0, 6], [12, 6, 0, 0, 6, 6, 6, 2], [0, -4, -14, 0, -10, 4, 10, 0], [0, 4, 4, 0, -12, -4, 12, 0], [20, 0, 0, 0, -2, 0, -2, 4], [0, 8, 12, -8, 6, -8, -6, 0], [-9, 9, 0, 0, 5, 9, 5, -13], [0, -9, -10, -4, -12, 9, 12, 0], [0, 2, -2, 8, -12, -2, 12, 0], [-13, 5, 0, 0, -4, 5, -4, -11], [0, -4, 30, -8, 2, 4, -2, 0], [-10, 8, 0, 0, 6, 8, 6, 0], [0, -9, 0, -17, 1, 9, -1, 0], [0, 14, 12, 0, 8, -14, -8, 0], [38, -4, 0, 0, 0, -4, 0, -2], [0, 11, -12, 3, -5, -11, 5, 0], [-14, -6, 0, 0, 1, -6, 1, -4], [0, 6, -12, 8, 8, -6, -8, 0], [13, -1, 0, 0, -4, -1, -4, 3], [-2, -1, 0, 0, 4, -1, 4, -6], [0, 16, 6, 0, 0, -16, 0, 0], [3, -3, 0, 0, -7, -3, -7, 7], [18, -6, 0, 0, -10, -6, -10, -4], [35, -2, 0, 0, -1, -2, -1, -9], [6, -6, 0, 0, -6, -6, -6, -4], [0, 1, 24, 7, 9, -1, -9, 0], [0, 2, 12, -2, 6, -2, -6, 0], [0, -15, -10, -10, -10, 15, 10, 0], [0, -3, 22, 0, 0, 3, 0, 0], [0, -6, 24, -14, 10, 6, -10, 0], [10, -10, 0, 0, 0, -10, 0, -4], [0, -4, 8, 0, -4, 4, 4, 0], [-6, -14, 0, 0, -10, -14, -10, 2], [-6, 4, 0, 0, 0, 4, 0, 8], [0, 10, 14, 6, 6, -10, -6, 0], [18, -2, 0, 0, 0, -2, 0, -4], [0, -12, 4, -6, -10, 12, 10, 0], [-14, 4, 0, 0, -2, 4, -2, 8], [0, 6, 16, -2, 1, -6, -1, 0], [-34, 5, 0, 0, -4, 5, -4, 2], [-16, -4, 0, 0, 8, -4, 8, 16], [-21, -15, 0, 0, 1, -15, 1, 11], [-4, -10, 0, 0, 14, -10, 14, 2], [0, 5, 14, -10, 2, -5, -2, 0], [0, -6, 6, 4, 16, 6, -16, 0], [22, -6, 0, 0, -16, -6, -16, 0], [0, -2, -2, 10, -3, 2, 3, 0], [6, -1, 0, 0, 4, -1, 4, 6], [-14, 8, 0, 0, -10, 8, -10, -8], [0, 14, -30, 10, -5, -14, 5, 0], [4, 4, 0, 0, -15, 4, -15, -12], [0, -14, 12, -6, 2, 14, -2, 0], [0, 3, -48, -3, -5, -3, 5, 0], [17, 3, 0, 0, 3, 3, 3, -7], [4, -12, 0, 0, 12, -12, 12, -2], [34, -2, 0, 0, 16, -2, 16, 10], [0, 16, 22, 0, 15, -16, -15, 0], [0, 9, 12, 1, -7, -9, 7, 0], [0, 8, 0, 0, 2, 8, 2, 6], [0, 2, -20, 6, 2, -2, -2, 0], [0, 7, -32, 5, -7, -7, 7, 0], [20, 2, 0, 0, -8, 2, -8, 2], [0, -4, -4, 2, 2, 4, -2, 0], [0, 2, -4, 0, -14, -2, 14, 0], [-10, -6, 0, 0, -7, -6, -7, -8], [22, 2, 0, 0, -12, 2, -12, 2], [12, 12, 0, 0, -6, 12, -6, -10], [0, -14, -6, 2, -14, 14, 14, 0], [0, -14, 26, -12, 0, 14, 0, 0], [14, 0, 0, 0, 4, 0, 4, 0], [0, 11, 16, 13, 11, -11, -11, 0], [-10, -16, 0, 0, -12, -16, -12, -4], [0, -5, 12, 5, -13, 5, 13, 0], [0, -11, -38, 2, -2, 11, 2, 0], [0, -6, 20, 0, 8, 6, -8, 0], [20, -4, 0, 0, 3, -4, 3, 0], [12, -2, 0, 0, -4, -2, -4, 8], [0, 2, 34, 10, 5, -2, -5, 0], [-25, 4, 0, 0, -1, 4, -1, -5], [0, 6, -8, -6, -9, -6, 9, 0], [-21, 9, 0, 0, 5, 9, 5, 11], [-12, 4, 0, 0, -6, 4, -6, -2], [0, 7, -40, 9, -1, -7, 1, 0], [0, 4, -24, 2, -6, -4, 6, 0], [0, 11, -26, 6, 6, -11, -6, 0], [0, 2, -8, 2, 11, -2, -11, 0], [-18, 10, 0, 0, 3, 10, 3, -4], [-18, 0, 0, 0, 2, 0, 2, -4], [0, 1, -20, -5, 3, -1, -3, 0], [19, -6, 0, 0, -13, -6, -13, 7], [0, -2, 0, 0, 0, -2, 0, 0], [-48, 8, 0, 0, 6, 8, 6, 2], [0, -11, 20, -5, 7, 11, -7, 0], [0, 2, -28, -10, -5, -2, 5, 0], [-8, -14, 0, 0, -4, -14, -4, 12], [0, -4, 14, -8, 5, 4, -5, 0], [-2, 6, 0, 0, 12, 6, 12, 14], [0, 10, 36, -2, 10, -10, -10, 0], [24, 8, 0, 0, -6, 8, -6, -24], [0, 7, 6, -6, 10, -7, -10, 0], [-12, 2, 0, 0, 18, 2, 18, -6], [-10, 8, 0, 0, -20, 8, -20, -12], [0, 4, 38, -8, 8, -4, -8, 0], [12, -14, 0, 0, 8, -14, 8, -6], [-2, -10, 0, 0, 0, -10, 0, 16], [0, -6, 14, 2, 2, 6, -2, 0], [21, 12, 0, 0, 1, 12, 1, -11], [28, -2, 0, 0, 0, -2, 0, 8], [0, 6, 16, 14, -10, -6, 10, 0], [0, -4, 2, -24, 7, 4, -7, 0], [-19, 7, 0, 0, -4, 7, -4, 7], [0, -12, -6, -6, 0, 12, 0, 0], [-30, -2, 0, 0, 10, -2, 10, 0], [-32, -2, 0, 0, -16, -2, -16, -6], [13, 3, 0, 0, -10, 3, -10, -5], [0, 8, 6, -8, -8, -8, 8, 0], [0, -11, 0, 9, -19, 11, 19, 0], [0, -17, 2, 2, 2, 17, -2, 0], [0, 10, 0, -10, 4, -10, -4, 0], [0, -6, 0, 8, -18, 6, 18, 0], [0, -1, -36, -1, -9, 1, 9, 0], [-18, -8, 0, 0, 2, -8, 2, 0], [0, -24, 10, -10, -6, 24, 6, 0], [-5, 1, 0, 0, -14, 1, -14, -7], [0, 2, 20, -4, -4, -2, 4, 0], [7, 21, 0, 0, 9, 21, 9, -9], [0, 4, 8, -16, 5, -4, -5, 0], [36, -12, 0, 0, -18, -12, -18, 6], [10, -4, 0, 0, -20, -4, -20, -12], [-20, 13, 0, 0, 16, 13, 16, 10], [-52, 0, 0, 0, 2, 0, 2, 0], [-2, 2, 0, 0, -7, 2, -7, 0], [0, -7, -2, 2, 6, 7, -6, 0], [-4, -4, 0, 0, -6, -4, -6, -8], [-6, -12, 0, 0, 0, -12, 0, 0], [0, -10, 8, -2, -1, 10, 1, 0], [-29, 4, 0, 0, -5, 4, -5, 3], [26, -4, 0, 0, 12, -4, 12, 0], [0, 5, 24, 13, 9, -5, -9, 0], [0, 21, 24, 13, 19, -21, -19, 0], [0, 10, -14, 16, -8, -10, 8, 0], [0, -5, 10, -2, -10, 5, 10, 0], [-6, 18, 0, 0, 5, 18, 5, -12], [0, -7, -4, -7, 15, 7, -15, 0], [4, 6, 0, 0, -10, 6, -10, -8], [42, -8, 0, 0, -4, -8, -4, -4], [0, -10, 38, 4, 8, 10, -8, 0], [0, 7, -36, 7, 3, -7, -3, 0], [0, 2, -22, -2, 1, -2, -1, 0], [4, -8, 0, 0, 16, -8, 16, 12], [0, -14, -8, 10, -9, 14, 9, 0], [-3, -1, 0, 0, 12, -1, 12, -5], [0, 15, -40, 9, -9, -15, 9, 0], [0, -13, -10, -12, 4, 13, -4, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_1680_ba_Hecke( : Kf := Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_1680_2_ba_a();".
// 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_1680_2_ba_a(:prec:=8)
    chi := MakeCharacter_1680_ba();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 2));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(1999) - 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_1680_2_ba_a();".
// 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_1680_2_ba_a( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_1680_ba();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<11,R![-58, -48, -1, 6, 1]>],Snew);
    return Vf;
end function;