
// Make newform 1045.2.a.g in Magma, downloaded from the LMFDB on 13 January 2026.
// To make the character of type GrpDrchElt, type "MakeCharacter_1045_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_1045_2_a_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_1045_2_a_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, -3, 25, 0, -10, 0, 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], [-3, 7, 0, -7, 0, 1], [9, 7, -3, -7, 0, 1], [3, -22, 0, 10, 0, -1], [3, 4, -6, -1, 1, 0]];
    Rf_basisdens := [1, 1, 3, 3, 3, 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_1045_a();"
function MakeCharacter_1045_a()
    N := 1045;
    order := 1;
    char_gens := [837, 761, 496];
    v := [1, 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_1045_a_Hecke( : Kf := Kf)
    return MakeCharacter_1045_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]];
    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, 1, 0, 0, 0, 0], [1, 0, 0, -1, 0, 0], [1, 0, 0, 0, 0, 0], [1, 1, 0, 0, -1, 0], [-1, 0, 0, 0, 0, 0], [-2, -1, 0, 1, 0, 0], [0, -1, 2, -1, 0, 0], [-1, 0, 0, 0, 0, 0], [1, -1, -1, 0, 1, 0], [-1, 1, -1, 1, -1, 1], [0, -2, 0, 0, -1, 0], [2, 0, -1, -1, 1, 1], [5, 1, 1, 0, 0, 2], [2, 1, 1, 1, 1, 0], [4, -1, -1, 1, 0, 2], [0, -1, -2, 1, -4, -2], [6, 1, 0, 1, 0, 0], [-2, 2, 0, -1, 2, -1], [4, 0, 3, 1, 2, 1], [-4, -2, 2, -1, -1, -3], [-4, 0, -3, -2, 1, 0], [2, 0, 1, -1, 1, -1], [4, -1, -4, 3, -2, -2], [4, 1, -1, -2, 1, -1], [5, 1, 4, -2, -2, -2], [1, 0, 3, 3, 0, 0], [3, 0, 1, 1, 2, -2], [5, -1, -1, 1, -2, 1], [-1, 0, 0, 1, 1, 0], [7, 2, 3, 2, 0, 1], [1, -1, -6, 3, 1, 3], [2, -4, -1, -1, -2, -3], [-4, -3, -1, 1, 2, -2], [-2, -1, 0, -3, -2, 2], [3, 0, 2, -2, -3, -1], [-9, 1, 1, 5, -3, -1], [-7, -1, 0, 4, 1, 0], [2, -4, 2, 2, -1, 2], [4, 2, -4, 3, 0, 3], [9, 4, 2, -1, -1, 0], [5, -2, 4, -3, 1, -2], [-8, 2, -2, -1, 1, -1], [-8, -3, 0, 6, 1, -1], [-2, -4, 2, -5, -3, -5], [-6, -1, 4, -3, 1, 2], [-12, 4, 5, 0, 3, 0], [-1, 3, 0, 2, -3, -2], [2, -7, -1, 1, 3, 0], [2, 4, 1, -1, 4, 5], [-1, 1, 3, -5, 0, 1], [-7, -6, 0, 0, 0, -1], [5, 3, -1, 0, 2, -2], [-6, -7, -3, 3, 3, 0], [0, 5, -2, 0, 3, 1], [-3, 0, 1, 1, -5, -4], [-5, -5, -1, 1, 5, 1], [6, 0, 4, 1, 2, -1], [-1, 6, -2, 4, -4, -1], [-2, -1, -7, 6, 1, 3], [-3, -1, 0, -7, -1, 3], [2, 6, 3, -3, -1, -1], [4, 4, -3, 2, 2, -2], [10, -3, 1, -6, -3, -1], [-8, -5, -2, 2, 6, 3], [-6, 4, 0, 1, -4, -1], [4, 4, 4, 0, 0, -2], [12, -4, 5, -3, 3, 3], [7, 2, -1, -5, 3, -2], [-3, 0, 5, -2, -3, 1], [-1, 1, -1, 0, -2, -4], [-5, 5, 1, 6, 8, 2], [-7, 7, 2, 1, 7, 1], [-2, 4, 3, 0, -1, -2], [10, -11, 3, -4, 5, -1], [2, -1, -2, 0, -2, 3], [4, 5, -2, 3, 2, -4], [-1, -6, 4, -7, 3, 2], [-1, 1, 1, -2, 3, 4], [2, 1, -4, 3, 4, 0], [4, 2, 1, -5, -2, 3], [10, -3, -1, 2, -6, -3], [-4, -9, 1, 7, -1, 0], [3, 2, 9, 4, 4, -3], [8, 3, -3, -3, 1, 2], [-15, 7, 1, 4, -4, 2], [-6, 9, -2, 2, 4, -1], [-7, 3, -11, 4, 5, 2], [-18, -2, -3, 11, 1, -1], [11, -4, -9, 5, -2, 4], [3, 0, 1, 4, -4, -5], [10, -7, 1, -7, 1, -4], [2, -3, 1, -1, -3, -6], [14, 6, 0, 0, 5, 2], [12, -2, -2, -9, -5, 1], [11, -3, -8, 4, 1, -2], [3, 3, 0, 5, -4, -3], [-13, 5, -5, -1, -3, -1], [22, 4, -1, -3, 5, -1], [-3, 4, 8, 1, 7, 0], [-15, 0, -12, 2, 5, 1], [1, 13, -2, 1, 4, 1], [-8, 4, 3, 1, -7, -7], [-7, 0, -1, 10, 4, 3], [3, -12, -2, 1, 3, 4], [3, -8, 5, -4, 9, 5], [10, 0, 3, -1, 5, -3], [11, -2, -2, 2, 2, 1], [-8, 9, 0, 2, -1, 1], [4, -9, -4, -2, -5, -3], [-12, -9, 1, 1, 2, 0], [10, 1, -5, 3, -4, 4], [-16, -1, -5, 0, -8, -7], [-3, 2, -3, 6, -2, -1], [8, -3, -3, -4, 8, 5], [-12, 5, 4, 2, -3, -1], [4, 4, 3, -7, -6, -1], [20, 3, 2, -3, 0, 4], [21, 1, 6, -1, -3, 5], [11, 2, -7, 2, 1, 7], [9, 1, -7, 0, 1, 2], [-6, -9, -3, 8, -2, 3], [-10, -12, 1, 0, 2, 2], [3, 4, 1, -1, 6, 2], [-10, 9, 0, -7, -3, -2], [12, -12, -4, 6, -1, 4], [-15, -1, -1, 5, 3, -3], [-9, 0, -3, 15, -1, 0], [7, -8, 0, -6, 0, 3], [-3, 9, 6, 8, -2, 2], [-5, -5, 4, -2, -1, 0], [-7, 9, 14, -2, -2, 0], [0, 8, 2, -13, -1, 3], [-3, -5, 0, -8, 7, 2], [4, -1, 0, -1, 0, 0], [5, 11, -2, -3, -2, 5], [-15, 6, 4, -7, 3, 0], [7, -4, -12, 6, -9, -1], [10, 0, -5, 1, -6, -1], [7, -2, 15, -3, -6, -2], [-15, -8, 0, 1, 5, -6], [3, -4, -7, 7, 0, -8], [3, 13, -7, 3, -1, 3], [14, -6, 4, -4, -3, 2], [-6, -8, 0, -2, 6, 0], [9, 2, 12, -6, -5, -5], [-17, -3, -7, 7, -6, -5], [-20, 0, -5, -1, 3, -1], [5, -3, -7, -1, -2, 3], [0, -6, -8, 0, 6, -2], [-18, -5, -1, -4, -3, 7], [3, -11, -7, 5, -9, -3], [14, 3, 6, -8, 11, 3], [-8, 7, 7, 0, -4, -1], [2, 3, 9, -14, 2, -1], [31, -5, 9, -13, 7, -5], [9, 6, 1, -4, 12, 3], [-10, -10, 0, -9, 0, 1], [-4, 1, 2, 9, 11, 2], [-13, -11, -4, 19, -6, -1], [-16, -3, -4, -1, 11, 4], [21, -2, 0, -4, -5, 3], [9, 14, -8, -3, 8, 2], [-10, 2, -2, 8, -9, 2], [-1, 21, 3, -7, -5, -5], [-9, -2, -1, 10, 2, -7], [-12, -4, -5, 0, -1, 8], [-28, 4, -17, 19, 7, 5], [-16, 3, -4, 10, 1, -1], [-20, -7, -6, -5, -4, 2], [-16, 12, 11, 2, -2, 2], [-10, -4, -13, 14, -2, -2], [10, -9, 9, -8, 2, -5], [-3, -6, -3, -2, -3, -13], [-9, -12, -1, -9, -9, 0], [-6, -1, -11, 4, -8, 5], [2, -15, -4, 6, -7, -5], [10, -14, 2, -6, 0, 2], [2, -9, 16, -5, -4, -2], [5, -7, -9, -3, -3, 5], [-3, 0, -13, 6, -8, -3], [1, 1, 8, -1, 8, 3], [-8, -11, 4, -10, -3, -5], [16, -9, 4, -16, -6, -5], [1, 11, 7, 3, 5, -1], [-11, -2, 11, -6, 5, 3], [5, -3, 12, -3, -4, 7], [-10, -8, -6, 5, -5, 5], [14, -9, 3, -10, -2, -1], [-37, 0, 5, 7, -7, -4], [26, 5, 3, -6, -3, 7], [6, 8, -2, 5, 9, 1], [7, -9, 4, -9, -1, -11], [-14, -13, -10, 6, 5, 7], [2, 11, -2, 6, 0, -1], [2, -9, -6, -6, 7, 3], [-9, 1, -7, 5, -2, -5], [-1, 3, 15, -3, 0, 1], [4, 2, -1, 2, -6, 0], [37, -3, 10, -9, 5, -5], [8, -2, 1, -8, 1, -10], [6, -2, 12, -1, -3, 1], [-2, -15, 1, -2, 7, 3], [16, 4, -7, 10, 2, -2], [-5, 8, 1, 20, 3, -1], [1, -9, -9, -2, 7, -2], [23, 0, -4, 3, 3, -6], [21, -7, 9, -17, 1, -9], [10, -4, 15, 3, 16, -3], [13, -13, 0, -7, -1, -1], [-5, 11, -4, 2, -8, 0], [5, 6, 5, -17, -1, 4], [-3, 3, -6, 5, 9, -1], [37, 2, 8, -15, -1, -6], [24, -6, 13, -9, 11, -5], [14, 5, -9, 4, 2, 3], [-4, -5, 3, -5, -8, -6], [-10, 6, -1, -4, -8, -10], [-8, -3, 7, 10, -8, 1], [-14, -10, -3, -15, -1, -1], [-1, -5, 3, -3, -2, -7], [4, -9, 0, 4, -4, -1], [-12, 20, 6, 13, -3, 5], [4, 4, -8, -5, 4, 3], [0, 7, 1, -11, -10, -6], [16, 17, -5, 7, 8, -2], [5, -1, 1, 0, 10, -4], [-12, -4, -14, 10, -1, 10], [7, 11, -11, 6, -5, 4], [21, 0, 0, -2, 14, 13], [6, 11, -11, 15, -4, -6], [-31, 11, -13, 13, -7, 5], [-12, -12, -11, 16, 4, -2], [11, -3, 8, 0, 5, 6], [14, 11, 4, -10, 3, 1], [-11, 0, -12, 6, -2, -11], [-7, -13, 6, 0, 12, -4], [-21, 6, -5, 7, -8, 0], [-10, 21, 5, -2, 4, 3], [-1, 1, -6, -13, 4, 5], [-17, 21, 11, 5, -4, 5], [-16, -21, -1, 0, 13, 5], [9, 14, -2, 15, 7, 8], [-6, -2, -10, -8, -5, 6], [16, 2, 2, -2, 16, 18], [3, -5, 6, -12, -9, -6], [-16, 0, -3, -10, -4, 4], [-29, 5, -18, 16, -7, -2], [9, -12, 3, 3, -2, 6], [7, -4, -2, -13, -5, -8], [-1, 2, -22, 6, -5, 7], [-11, -6, 10, -4, 11, 5], [18, 5, -8, 5, -4, -6], [4, -10, -5, -9, 12, -3], [-6, 8, 12, -10, 4, 10], [-24, -10, -5, 4, -7, -8], [14, -4, -5, 8, 5, 2], [9, 10, 8, 8, -1, 5], [-8, 0, 2, 9, -10, -9], [-5, 6, -9, 0, -6, -5], [1, -13, -2, -8, -4, -6], [13, 2, -1, 11, -3, -2], [7, 9, 10, 1, -10, 3], [4, -16, -7, -10, -8, -10], [-2, 15, 4, -8, -1, -5], [18, -2, -8, 7, 6, -5], [-16, 14, -3, 9, -9, 1], [11, -6, 18, -15, 8, 4], [8, 7, -5, 1, 7, 10], [28, -5, 8, -7, 17, 2], [-4, 0, -5, 3, 5, 7], [-9, -8, -6, 2, 7, -5], [9, 7, 9, -5, -13, -11], [22, 6, 13, 1, 3, 9], [2, -3, 9, -9, -11, -6], [10, 6, 1, -8, 12, 0], [-20, 4, -5, 5, 14, 5], [37, -5, 0, 7, 0, 9], [-5, 10, 7, -10, 17, 7], [-24, -7, -10, 5, 10, 0], [6, 1, 22, -10, -7, -3], [0, -7, 0, -7, 8, 2], [-9, 4, 17, -25, 5, 10], [1, -17, -9, -6, -11, -6], [6, 16, -6, 2, 6, 6], [14, -7, 6, -12, 12, 5], [-10, 22, 9, 12, 8, 10], [-2, -5, -11, -4, -1, -11], [20, -6, -10, -2, 3, 8], [26, 19, 7, -8, -15, 3], [-11, 6, -2, 1, 8, 2], [-16, 10, 7, 9, -3, -1], [-38, 0, 7, -2, -2, 2], [9, 16, 8, 5, 2, -4], [31, -3, 0, -15, 3, -3], [-8, 7, 9, -7, 5, 2], [-20, 1, -17, 9, -3, -4], [-15, 12, -3, 5, -10, -4], [-12, -20, 3, 2, 0, 2], [24, -7, 20, -4, 9, 1], [-14, -10, -8, -8, 4, 4], [-42, 1, -15, 7, 1, 0], [4, 11, -2, 7, -5, 10], [-37, 0, 10, 12, -2, -3], [34, -1, 5, -15, -13, 2], [20, -3, 9, 3, 2, -6], [22, -16, -2, -6, -13, -4], [29, 11, 7, -17, -1, 5], [0, -9, 6, 2, -5, -1], [-14, -13, 1, 5, -11, 6], [40, -1, -6, 3, -5, -2], [9, 3, -11, 5, 5, 11], [-27, -15, 3, -6, -9, -2], [-33, -6, -13, 15, 4, 8], [-6, 9, 4, 9, 20, 0], [-6, 0, 19, -8, -4, -4], [-19, -1, -1, 17, 14, -1], [37, 9, -2, -10, -6, 4], [-16, -11, 4, 9, -4, -2], [12, -3, 1, 2, -11, 3], [-2, -7, -8, 5, -1, 8], [8, -10, -12, 8, -1, -4], [25, 15, 6, -3, -9, -1], [19, 0, -13, -6, 0, 3], [-4, 0, -10, 15, 4, -7], [-1, 9, -15, -4, -21, 6], [0, 15, 15, -4, -6, -15], [20, 13, 3, 0, 2, -3], [-23, 3, -12, 11, -1, -1], [-4, -12, -1, 2, 1, -2], [22, 3, 21, -11, 0, 2], [29, 6, 4, -20, -3, 5], [-23, 8, 0, 17, 5, 6], [17, -5, 16, -23, 5, -3], [1, -6, 7, 11, 6, -8], [-7, 7, 5, -19, 0, 1], [15, 3, 12, -16, 10, 6], [1, -11, 10, -12, 2, 0], [-5, 9, -17, 12, 8, 8], [-18, 5, -8, -8, -5, -3], [-7, 15, -13, -6, 0, 0], [-3, 17, 5, 2, 18, 8], [9, 1, -4, 4, 4, 16], [-14, -11, 2, 5, 17, 4], [8, -26, -15, 8, 6, 8], [-4, -2, 0, -15, 7, -3], [12, 4, 12, -1, -5, -9], [24, 11, 8, -19, 0, 10], [-14, 0, 0, -1, 4, 3], [-12, -2, -10, 16, -5, 0], [21, -15, 22, -14, 16, -2], [-11, 8, -5, 2, -6, -5], [30, -17, 2, -16, 3, -9], [-13, 17, 5, 10, 15, 4], [-9, 11, 8, -8, -2, 6], [-21, 17, 3, -8, 5, -2], [-3, 10, 17, 3, 9, 8], [-17, -14, -2, -10, -3, -5], [20, 3, 1, -2, 11, 15], [-40, 3, -19, -7, 1, -6], [-2, -2, -15, 12, -12, -10], [0, 0, -1, 8, -19, -14], [13, -22, 1, -8, 5, 3], [14, 2, -9, 5, -3, 3], [6, 10, 11, -20, 1, 0], [-6, 20, -1, -1, -10, 9], [-4, 1, 7, 12, 7, -3], [11, 1, -5, -18, -8, 2], [13, -15, 1, -8, -17, -2], [18, -1, 7, -6, -19, -1], [6, -4, 2, 0, 9, 8], [12, -29, 5, -1, -6, 0], [1, 3, 11, -19, 1, -9], [-5, 5, -7, 6, -11, -8], [-17, 11, 2, -11, 0, 5], [-12, -5, -4, -10, -7, 11], [24, 1, 7, -3, -13, -10], [-33, 10, -14, 13, 12, 6], [-9, 6, 0, 3, -7, 16], [-6, -11, 19, -4, 11, -5], [-7, -6, 2, -11, -2, -2], [-7, 1, 16, 14, -12, -6], [27, 6, 10, 4, -1, -5], [16, 1, 6, -4, 18, 11], [23, -6, 1, -6, 3, -9], [17, 4, -3, -13, -9, 4], [9, 0, -9, 3, -18, -6], [-53, 0, -6, 5, -11, -10], [-5, 4, 10, -4, 9, 5], [-3, -3, 10, -2, -9, -14], [-18, 18, 14, 7, -5, -5], [4, 9, -9, 8, -10, -17], [41, -5, 0, 8, 0, -2], [77, 4, 1, 0, -7, -5], [33, 14, -4, 5, 4, -4], [-14, 5, 2, -3, 9, 6], [-1, -15, -5, -11, 1, -7], [-64, 7, -14, 11, 1, 0], [-29, -1, 6, -5, 11, 7], [-25, 7, -3, 10, -10, 6], [3, -2, -12, -5, -3, 12], [13, 8, 4, -17, 3, -8], [-13, -21, 14, -7, -1, -3], [24, 6, 21, -15, -11, -7], [22, -9, 11, -18, -5, 3], [-19, -10, -7, 3, 9, -12], [-14, 20, 11, 7, 11, 11], [1, -17, 2, -23, -5, -9], [63, 4, 12, -1, -7, 2], [-28, -7, -4, 20, 5, 1], [37, 8, -4, -11, 2, -2], [28, 5, -5, 14, 0, 5], [26, 1, -10, 13, -6, 6], [23, 1, 15, -10, -4, -4], [-23, 20, -7, 14, -20, -1], [-14, 16, 4, 3, 11, -5], [-37, 4, -8, 5, -3, 4], [14, 17, -7, -2, 9, -1], [16, 10, -7, -4, 12, -8], [-27, -11, -8, 1, -12, -1], [21, -4, 1, 17, 12, 8], [-10, -8, 9, -8, 9, -12], [6, -13, 9, -2, 20, -11], [-32, -12, -9, 10, -9, -14], [40, -33, -9, -12, 5, -7], [30, -25, -9, -4, -10, -5], [27, -15, -22, 10, -10, -4], [14, -5, 11, -24, -6, 1], [5, -11, 2, -19, -6, -5], [-8, -28, 22, -10, 3, -4], [-4, -6, -7, 5, 8, 19]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_1045_a_Hecke( : Kf := Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_1045_2_a_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_1045_2_a_g(:prec:=6)
    chi := MakeCharacter_1045_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_1045_2_a_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_1045_2_a_g( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_1045_a();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![-9, -3, 25, 0, -10, 0, 1]>],Snew);
    return Vf;
end function;