
// Make newform 2842.2.a.ba in Magma, downloaded from the LMFDB on 20 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_2842_a();"
// To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
// To make the newform (type ModFrm), type "MakeNewformModFrm_2842_2_a_ba();".
// 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_2842_2_a_ba();".
// 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 := [-7, -20, 22, 18, -13, -2, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0], [16, 47, -12, -5, 1, 0], [-9, 31, 21, -26, -3, 2], [65, -16, -35, 1, 2, 0], [63, 40, -72, -8, 6, 0], [-29, 84, 42, -52, -6, 4]];
    Rf_basisdens := [1, 11, 11, 11, 11, 11];
    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_2842_a();"
function MakeCharacter_2842_a()
    N := 2842;
    order := 1;
    char_gens := [1277, 785];
    v := [1, 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;

function MakeCharacter_2842_a_Hecke(Kf)
    return MakeCharacter_2842_a();
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 := [[-1, 0, 0, 0, 0, 0], [0, 0, 1, 0, 0, 0], [0, -1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [-1, 0, 0, 0, 1, 0], [0, 1, 0, 0, 0, 0], [0, 0, -2, -1, 0, 0], [0, 1, 0, 1, 0, 0], [-5, 0, 0, 0, 0, 1], [-1, 0, 0, 0, 0, 0], [0, 1, 2, 2, 0, 0], [-3, 0, 0, 0, -2, -1], [0, 1, -3, 0, 0, 0], [-4, 0, 0, 0, 0, -2], [0, 1, 0, -2, 0, 0], [4, 0, 0, 0, 0, -2], [0, 0, 0, 1, 0, 0], [0, 1, 3, 1, 0, 0], [-4, 0, 0, 0, 0, 0], [-3, 0, 0, 0, 0, 3], [0, -1, 1, -2, 0, 0], [-2, 0, 0, 0, 1, -1], [0, -1, 1, 2, 0, 0], [0, -3, -1, 0, 0, 0], [0, 0, -6, -1, 0, 0], [0, -1, -7, -1, 0, 0], [0, 0, 0, -2, 0, 0], [-2, 0, 0, 0, -2, 0], [4, 0, 0, 0, 0, -2], [-8, 0, 0, 0, 1, 1], [0, 0, 0, 0, 1, -3], [0, -1, 8, -1, 0, 0], [-4, 0, 0, 0, -3, 1], [0, 3, 3, 0, 0, 0], [-10, 0, 0, 0, 1, -3], [5, 0, 0, 0, -2, 1], [0, -4, 0, 2, 0, 0], [-13, 0, 0, 0, -1, -2], [0, 1, -7, 1, 0, 0], [0, 3, -2, 2, 0, 0], [8, 0, 0, 0, 0, 4], [0, -1, 6, -2, 0, 0], [6, 0, 0, 0, -3, 3], [-6, 0, 0, 0, 1, -1], [0, 0, 0, 0, 1, -1], [0, -3, -5, -5, 0, 0], [-14, 0, 0, 0, 0, 2], [0, 3, 7, 1, 0, 0], [0, -1, 3, -2, 0, 0], [0, -3, 3, -1, 0, 0], [0, 0, 0, 0, 2, 2], [0, 0, 0, 0, 4, 4], [0, -5, 2, 1, 0, 0], [0, 2, 5, -4, 0, 0], [0, -2, -9, 0, 0, 0], [-18, 0, 0, 0, 1, 3], [0, 0, -2, 0, 0, 0], [0, 1, -8, 0, 0, 0], [-8, 0, 0, 0, 1, 3], [-3, 0, 0, 0, -5, -2], [0, 0, 8, 1, 0, 0], [0, 0, 14, -2, 0, 0], [0, 3, 6, 5, 0, 0], [0, 5, 10, -2, 0, 0], [0, 3, -2, 1, 0, 0], [-10, 0, 0, 0, 2, 2], [-2, 0, 0, 0, -2, -6], [-4, 0, 0, 0, -2, -4], [-8, 0, 0, 0, -1, 1], [0, -3, -10, -4, 0, 0], [0, -3, 6, -1, 0, 0], [4, 0, 0, 0, 1, 1], [0, 1, 4, 0, 0, 0], [4, 0, 0, 0, -3, -1], [-4, 0, 0, 0, 4, -2], [0, 1, -3, 1, 0, 0], [7, 0, 0, 0, 0, -1], [0, 1, -8, 2, 0, 0], [-2, 0, 0, 0, -2, -2], [0, -6, 0, -3, 0, 0], [0, -4, -12, -1, 0, 0], [9, 0, 0, 0, 4, 1], [-10, 0, 0, 0, 0, -2], [0, 1, 9, -2, 0, 0], [0, 3, -3, 3, 0, 0], [1, 0, 0, 0, -5, -2], [-14, 0, 0, 0, -4, -4], [17, 0, 0, 0, -3, -4], [0, 2, 0, 2, 0, 0], [11, 0, 0, 0, 2, 3], [0, 3, 2, -5, 0, 0], [0, 5, 8, 4, 0, 0], [-6, 0, 0, 0, 2, -4], [0, 0, 0, 0, 4, 8], [-12, 0, 0, 0, 2, -2], [0, 3, -2, -2, 0, 0], [0, -1, -4, 4, 0, 0], [0, 5, 0, -3, 0, 0], [0, -1, -11, 0, 0, 0], [-8, 0, 0, 0, 6, 0], [4, 0, 0, 0, -3, 3], [20, 0, 0, 0, 4, -2], [0, -5, -6, 3, 0, 0], [-4, 0, 0, 0, 0, 6], [-22, 0, 0, 0, 3, 7], [0, 5, 7, 6, 0, 0], [0, 0, -18, 3, 0, 0], [0, 0, -3, -4, 0, 0], [0, 0, 0, 0, -3, -3], [0, 2, -12, -1, 0, 0], [0, 5, -12, 2, 0, 0], [34, 0, 0, 0, -1, -1], [-20, 0, 0, 0, 4, -2], [0, 1, -10, -3, 0, 0], [-4, 0, 0, 0, 4, 8], [-4, 0, 0, 0, 2, 8], [0, -1, 31, 0, 0, 0], [0, -5, -3, -7, 0, 0], [-4, 0, 0, 0, 0, -2], [19, 0, 0, 0, -3, -8], [0, -5, -10, -6, 0, 0], [7, 0, 0, 0, -1, -4], [0, -7, -5, 3, 0, 0], [-14, 0, 0, 0, -4, -6], [0, -4, -2, 1, 0, 0], [12, 0, 0, 0, -1, 1], [4, 0, 0, 0, -4, 2], [0, 2, 18, 0, 0, 0], [0, -3, 14, 2, 0, 0], [0, -5, -7, 3, 0, 0], [4, 0, 0, 0, 8, -2], [-4, 0, 0, 0, -6, -2], [20, 0, 0, 0, -4, 8], [-9, 0, 0, 0, 0, -1], [0, 2, -1, 6, 0, 0], [0, -4, -2, -3, 0, 0], [0, 1, 13, 3, 0, 0], [0, 2, -22, 3, 0, 0], [0, 0, -24, -6, 0, 0], [-22, 0, 0, 0, 3, 5], [0, 0, -8, 1, 0, 0], [22, 0, 0, 0, -2, -2], [-10, 0, 0, 0, 4, 10], [3, 0, 0, 0, 3, 4], [0, 3, 13, 3, 0, 0], [0, -3, -16, 0, 0, 0], [0, 5, 17, 1, 0, 0], [0, 7, 10, -3, 0, 0], [0, -7, 16, -1, 0, 0], [-9, 0, 0, 0, 2, 3], [-26, 0, 0, 0, 3, -5], [0, -6, -2, -3, 0, 0], [-22, 0, 0, 0, 6, -4], [0, 7, 2, 4, 0, 0], [-3, 0, 0, 0, -5, 2], [-2, 0, 0, 0, 7, -3], [17, 0, 0, 0, 6, 1], [0, -7, 10, -5, 0, 0], [0, 9, 2, 7, 0, 0], [0, 3, 22, 0, 0, 0], [0, 0, 0, 0, 0, 6], [23, 0, 0, 0, 5, 4], [-6, 0, 0, 0, -4, 6], [0, -6, 13, 4, 0, 0], [-17, 0, 0, 0, 3, 8], [0, -3, -20, -4, 0, 0], [-14, 0, 0, 0, -4, -6], [0, 8, 4, -8, 0, 0], [11, 0, 0, 0, 1, 6], [0, 2, -12, -2, 0, 0], [30, 0, 0, 0, 0, 6], [0, 1, 24, -2, 0, 0], [16, 0, 0, 0, 8, 0], [-16, 0, 0, 0, 7, -9], [0, 4, -30, 0, 0, 0], [0, -9, -10, 1, 0, 0], [-8, 0, 0, 0, -2, -10], [-13, 0, 0, 0, 4, -1], [0, -1, 10, 0, 0, 0], [0, 1, 14, -2, 0, 0], [-18, 0, 0, 0, 0, 10], [0, -10, -7, -6, 0, 0], [4, 0, 0, 0, 2, -8], [0, 10, -7, 8, 0, 0], [-22, 0, 0, 0, 2, -4], [0, -7, 8, 0, 0, 0], [-21, 0, 0, 0, 2, 5], [0, -4, 1, 4, 0, 0], [2, 0, 0, 0, 3, 5], [0, -3, -13, -1, 0, 0], [0, 2, 7, 0, 0, 0], [-28, 0, 0, 0, 6, 6], [6, 0, 0, 0, -8, -2], [0, -11, 1, -3, 0, 0], [-37, 0, 0, 0, 5, -2], [0, 4, 15, 2, 0, 0], [-18, 0, 0, 0, -6, -6], [0, 0, 0, 0, 5, 7], [0, -5, -8, 7, 0, 0], [0, 2, -10, -6, 0, 0], [16, 0, 0, 0, -2, -8], [0, -9, 3, 3, 0, 0], [0, -7, -11, 3, 0, 0], [0, -7, 23, -2, 0, 0], [0, 8, 5, 6, 0, 0], [0, 3, -22, 2, 0, 0], [0, -5, 8, 0, 0, 0], [-24, 0, 0, 0, -9, -3], [1, 0, 0, 0, -11, -8], [0, 0, -21, -6, 0, 0], [-2, 0, 0, 0, 2, 10], [0, -7, -16, 0, 0, 0], [28, 0, 0, 0, 10, 2], [0, -1, -12, 5, 0, 0], [0, -1, -12, 2, 0, 0], [0, 2, 23, 6, 0, 0], [35, 0, 0, 0, 0, 1], [0, -4, -8, -3, 0, 0], [-30, 0, 0, 0, 0, -6], [-11, 0, 0, 0, 8, -3], [5, 0, 0, 0, 0, -3], [0, -1, 7, 5, 0, 0], [-10, 0, 0, 0, 4, 0], [-32, 0, 0, 0, 5, 1], [0, 7, 5, -2, 0, 0], [20, 0, 0, 0, -4, 6], [0, -11, 15, 0, 0, 0], [4, 0, 0, 0, -3, 9], [0, -3, -2, -2, 0, 0], [-14, 0, 0, 0, -9, -1], [-20, 0, 0, 0, -8, -2], [0, 9, -1, 4, 0, 0], [-46, 0, 0, 0, -4, -2], [-42, 0, 0, 0, 4, -4], [0, -6, 12, -7, 0, 0], [0, -9, -8, 6, 0, 0], [0, -1, 1, 2, 0, 0], [-15, 0, 0, 0, -2, 7], [8, 0, 0, 0, 0, 12], [0, 15, 2, 0, 0, 0], [-9, 0, 0, 0, 9, 8], [0, 2, 16, -9, 0, 0], [0, -14, 6, -2, 0, 0], [31, 0, 0, 0, 2, -7], [0, 1, 14, 3, 0, 0], [0, -8, 14, -8, 0, 0], [0, -2, -16, -12, 0, 0], [0, 12, -14, -1, 0, 0], [2, 0, 0, 0, -9, -1], [28, 0, 0, 0, 0, 8], [-13, 0, 0, 0, 4, -13], [0, 14, -13, 6, 0, 0], [18, 0, 0, 0, 2, 8], [0, -4, 4, 9, 0, 0], [0, -6, 14, 6, 0, 0], [-6, 0, 0, 0, 4, 10], [2, 0, 0, 0, -2, -14], [0, 0, -21, 6, 0, 0], [0, 3, -2, 2, 0, 0], [0, -3, 8, -9, 0, 0], [14, 0, 0, 0, -1, 5], [13, 0, 0, 0, 3, 0], [0, 1, 4, -4, 0, 0], [0, 12, -2, 6, 0, 0], [0, -8, 20, 3, 0, 0], [0, 6, 15, 8, 0, 0], [11, 0, 0, 0, -2, -3], [0, -4, 12, 9, 0, 0], [-20, 0, 0, 0, -6, 2], [34, 0, 0, 0, -2, -2], [0, 3, 16, 6, 0, 0], [20, 0, 0, 0, 5, 11], [0, 4, -13, -6, 0, 0], [22, 0, 0, 0, -7, -9], [0, 12, 8, 1, 0, 0], [0, -5, 0, 8, 0, 0], [-45, 0, 0, 0, 3, -6], [-10, 0, 0, 0, -8, -12], [32, 0, 0, 0, -5, -9], [0, 7, 25, 8, 0, 0], [0, 5, 15, -7, 0, 0], [29, 0, 0, 0, -2, -11], [0, 6, 6, -4, 0, 0], [0, 1, 20, 4, 0, 0], [0, -2, -1, 2, 0, 0], [0, 0, 0, 0, 1, 17], [-6, 0, 0, 0, 12, 16], [-56, 0, 0, 0, 6, -8], [0, 10, 8, 6, 0, 0], [0, 3, -20, -13, 0, 0], [-14, 0, 0, 0, -2, -2], [0, 4, -2, -7, 0, 0], [-28, 0, 0, 0, -2, 0], [0, 3, -14, -7, 0, 0], [21, 0, 0, 0, 2, 11], [0, -7, 30, 0, 0, 0], [0, 7, 8, -6, 0, 0], [0, 1, -2, 10, 0, 0], [0, 1, -1, 14, 0, 0], [0, -7, -20, 3, 0, 0], [0, 3, 17, 2, 0, 0], [-28, 0, 0, 0, 8, 2], [-16, 0, 0, 0, -4, -16], [54, 0, 0, 0, 0, -4], [-41, 0, 0, 0, 3, -10], [16, 0, 0, 0, 14, 2], [6, 0, 0, 0, 0, -4], [0, -13, 10, -4, 0, 0], [49, 0, 0, 0, -8, 11], [-10, 0, 0, 0, -9, -9], [0, -15, -11, 7, 0, 0], [28, 0, 0, 0, -8, -6], [-20, 0, 0, 0, 10, -6], [-22, 0, 0, 0, -9, -1], [-22, 0, 0, 0, 2, 0], [0, 2, 25, -6, 0, 0], [0, 2, 9, 8, 0, 0], [18, 0, 0, 0, -6, 8], [0, 4, 7, 2, 0, 0], [12, 0, 0, 0, 3, -9], [0, -13, -16, 5, 0, 0], [-11, 0, 0, 0, -3, 4], [0, -9, 2, -8, 0, 0], [2, 0, 0, 0, 6, 12], [-44, 0, 0, 0, 6, -6], [0, -7, 25, -4, 0, 0], [6, 0, 0, 0, 9, 5], [0, -7, 7, -6, 0, 0], [52, 0, 0, 0, -2, 2], [14, 0, 0, 0, -11, -15], [-19, 0, 0, 0, 4, 1], [10, 0, 0, 0, -10, -6], [0, 5, -25, 3, 0, 0], [0, -9, -20, -1, 0, 0], [-28, 0, 0, 0, 4, 4], [0, -12, 8, 3, 0, 0], [-16, 0, 0, 0, 10, -4], [0, -12, -2, 9, 0, 0], [0, -9, 7, -6, 0, 0], [0, 0, 18, 8, 0, 0], [-9, 0, 0, 0, -16, -5], [8, 0, 0, 0, 8, -10], [0, -2, -44, -2, 0, 0], [-11, 0, 0, 0, 8, 3], [-2, 0, 0, 0, 7, 11], [46, 0, 0, 0, 4, -4], [0, 2, -32, 2, 0, 0], [11, 0, 0, 0, -7, 4], [0, 5, 14, 2, 0, 0], [0, 17, -19, 3, 0, 0], [0, 7, 25, 10, 0, 0], [-25, 0, 0, 0, -11, -4], [-14, 0, 0, 0, -2, 10], [0, 9, 3, -1, 0, 0], [15, 0, 0, 0, -14, -3], [0, 4, 8, 7, 0, 0], [0, 5, 52, 2, 0, 0], [0, -10, -12, -1, 0, 0], [-24, 0, 0, 0, -4, 10], [71, 0, 0, 0, -4, 1], [-24, 0, 0, 0, 10, 8], [0, -13, -34, 7, 0, 0], [28, 0, 0, 0, -9, 3], [-24, 0, 0, 0, 6, 2], [0, 13, 20, -7, 0, 0], [12, 0, 0, 0, -8, -6], [0, -12, 4, 6, 0, 0], [40, 0, 0, 0, -2, 6], [-2, 0, 0, 0, -1, -7], [-27, 0, 0, 0, -17, -2], [0, 0, -38, -5, 0, 0], [-1, 0, 0, 0, -4, -15], [24, 0, 0, 0, 0, 18], [0, -1, 19, 9, 0, 0], [22, 0, 0, 0, -5, -13], [0, 2, -39, -8, 0, 0], [72, 0, 0, 0, -4, 8], [0, -4, -14, 7, 0, 0], [0, 9, 14, 17, 0, 0], [0, 22, -13, 6, 0, 0], [0, -5, 11, -1, 0, 0], [56, 0, 0, 0, -2, 6], [-22, 0, 0, 0, -3, -1], [2, 0, 0, 0, 8, -4], [0, 2, -14, -3, 0, 0], [0, -4, -6, -2, 0, 0], [-24, 0, 0, 0, 2, 2], [0, 17, 16, 4, 0, 0], [-43, 0, 0, 0, 9, 0], [0, -7, 12, 0, 0, 0], [16, 0, 0, 0, 6, 8], [0, 13, -28, 6, 0, 0], [18, 0, 0, 0, -10, 8], [0, -3, 8, 17, 0, 0], [-6, 0, 0, 0, 13, -5], [-16, 0, 0, 0, -8, -4], [0, 8, 4, -2, 0, 0], [0, 3, 11, 4, 0, 0], [-4, 0, 0, 0, 6, 6], [-8, 0, 0, 0, -8, 2], [0, 1, 8, 14, 0, 0], [-18, 0, 0, 0, 12, 24], [-50, 0, 0, 0, -5, -3], [0, 5, 6, -1, 0, 0], [0, 7, 18, 8, 0, 0], [0, 3, -17, -1, 0, 0], [26, 0, 0, 0, 17, 1], [4, 0, 0, 0, 7, -5], [0, 2, -1, 12, 0, 0], [0, 1, -27, 6, 0, 0], [0, 10, -1, -4, 0, 0], [34, 0, 0, 0, -7, 1], [-20, 0, 0, 0, -1, -3], [-14, 0, 0, 0, -8, -6], [-66, 0, 0, 0, 5, 7], [0, -5, -49, 3, 0, 0], [4, 0, 0, 0, -2, 6], [0, -9, 7, -5, 0, 0], [0, 6, 6, 13, 0, 0], [0, 7, -14, -12, 0, 0], [46, 0, 0, 0, 1, -7], [0, 4, -36, 4, 0, 0], [2, 0, 0, 0, -13, -11], [0, -13, 10, -7, 0, 0], [0, 11, -6, -13, 0, 0], [0, 15, 18, -10, 0, 0], [20, 0, 0, 0, 11, 1], [-18, 0, 0, 0, 9, 7], [0, -4, 30, 5, 0, 0], [0, 13, -18, 8, 0, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_2842_a_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_2842_2_a_ba();".
// 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_2842_2_a_ba(:prec:=6)
    chi := MakeCharacter_2842_a();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 2));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(2999) - 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_2842_2_a_ba();".
// 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_2842_2_a_ba( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_2842_a();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<3,R![-2, 0, 1]>,<5,R![-8, 0, 324, 0, -36, 0, 1]>],Snew);
    return Vf;
end function;